Can some on explain to some player on LoL what is the main role of a jungler is it ganking and covering lanes while some one is back or is it warding and getting gold for your team.It make me so mad that a player cant understand when a jungler is a low lvl he cant gank, for example if bot lane is lvl 6 and I'm lvl 5 should I gank and even when i do it is a fail cus the enemy team will have more chance of surviving. So pls can someone explain?
There a lot going on in that paragraph. Can you ask a question with one sentence. Preferably full and with proper grammar and punctuation?
If your bot lane is level 6 and you're only level 5, you need to do some more effective farming as you shouldn't be getting out leveled by bot lane.
As a jungler your main purpose is to provide map pressure. That can be ganking, counter jungling, taking objectives, vision control, or if none of that is possible you farm so that you keep up with the game.
If you're a jungler that comes along with some CC, you shouldn't have too many problems ganking from lower level. For example, Rek'sai has a knockup, so even though I may be behind solo laners in level, I can gank mid, and provide a knockup. That is often enough CC to kill the enemy laner, or at minimum cause them to blow their flash. There's a lot that goes into the math when considering ganking, level isn't the only factor.
If you're ganking mid lane for example you also need to look at the health of the enemy laner, your health, your mid laner's health, whether there are flashes in play, if the enemy mid is pushed up or not, and if there's a potential for the enemy jungler to come in with a counter gank.
There's also a common misconception, you don't need to secure a kill with each gank, blowing a summoner spell is a win, simply pushing the enemy out of lane is also a win, because you've typically caused them to take an unfavorable back instead of when they wanted to back.
Ok.....so first of all you can't ask this one generic question for all junglers, because all junglers have different play styles and have different sustain in jungle. There are a few different things that come into play while you are jungling, in MY OPINION those are surviving in jungle, CC and/or Damage, Vision, Your ability vs the enemy's ability and timing
Surviving - Some junglers can go through all 6 camps and still be at nearly full health and some might be nearly dead after their last camp. So if i have full health I look for a good ganking opportunity in the closest lane and if it feels right, I go in.
CC and/or Damage - Most champions these days that jungle tend to have CC abilities but there still are some that don't. If you are ganking early than you have to make sure that you will be able to earn enough time for yourself and you team to get a kill which is why CC is important. Examples of these champions would be 
, 
and 
. But there are some champions who don't have CC or at least don't have CC early enough to use it for an early gank. These champions rely on damage and the example would be 
and 
. Warwick's ult is kind of a CC skill since it stops the enemy in its place for a while but that's not until level six. That being said you can still gank if the opportunity presents so always keep an eye on the lanes closest to you.
Vision - Vision is a really important part of jungling. A lot of people say that buying wards is just for supports and well....those people are stupid. Vision in the jungle is very important especially close to the lanes, so every time you go back to the fountain please buy a ward and don't just leave that to your support or the rest of the team. Vision really helps your team because it can prevent the enemy jungler from ganking. Also vision can help you spot their jungler and if he is in the top lane and you see a ganking opportunity in the bot lane, go for it, because you know he will never make it there in time. Also make sure you communicate with your team about where the enemy has their wards in the river because i always see junglers sitting in the bush where the enemy team has a ward and that's just a waste of time.
Your vs the enemy's ability - You can do everything right but if they are better at league than you and not at an actual disadvantage then they will most likely get away but might burn their summoner spell in the process.
Timing - your timing as to when you jungle is really crucial, most of the time if you can't get a kill but make the enemy go back to base and/or burn their summoner spells, its still a successful gank as it gives your team an advantage. Also don't jsut stand in a bush while the enemy is under their own tower, hoping that they might over extend because that is a waste of time, time that could have been spent farming or warding.
That being said role of jungler depends on your own play style + the champion that you use, though if you wait until mid game to start ganking, it might be too late for your team. Also don't be afraid to gank just because you are 1 or 2 levels behind the enemy tam because you can still easily win in a 2 v 1 or a 3 v 2 as long as your team helps, oh and always ping when coming into lane because sometime people might not notice and then you fail the gank and maybe even give away a kill. Also, as a jungler I feel like making sure keeping the dragon warded to prevent the enemy team from taking it is my responsibility unless my bot lane says that they will keep it warded
Accept that you will have to make tough choices. Your top lane will hate you for not camping top like the enemy jungler. Meanwhile your bot lane loves you for giving them 5 kills.
If you are being out leveled by bot lane as a jungler you are already doing something terribly wrong in your early game.
Ganking isn't just about levels though. If the enemy jungler showed top and somehow bot lane out levels you it is still gankable depending on who you are playing, who they are playing, what summoners are up, their health, your health, what cc your bot lane has - theres a lot to consider.
Holding lanes while they back can be good if you have the health to do it safely and not risk giving a kill to the person that the laner just backed to avoid giving a kill to. Holding lanes can also be bad in cases such as the enemy forcing your bot lane to back and the enemy jungler is bot side near drag because your show on map might enable them to drag.
Pretty much every second you need to be thinking of where you should be, where you should be going and what you need to be doing or setting up to do in order to be as efficient for your team as possible.
