Okay, you seem new so I'm going to explain wards to you, and then I'll answer whichever questions are left.
There are three main types of wards: Stealth, Vision, and Farsight.
Stealth wards come from either the warding trinket (the yellow one) or from Sightstones (an item from the shop that allows you to place wards), or from the Tracker's Knife (a jungle item that behaves similarly to a Sightstone). These wards are invisible, except for a short duration upon placing them. These wards are revealed when the enemy uses a Vision ward (see below), or a Sweeper on them, or smites Wraiths and walks near them (will be explained later). When they are visible, they can be destroyed with three auto-attacks from champions, or when they expire. You can have up to three of these wards on the map at a time. Use these invisible wards to gain vision on important locations and locations where the enemies are likely to be.
Vision (pink) wards are purchased from the shop for 75 gold each. They are visible to your enemies. These wards allow you to see invisible champions (like Rengar), invisible traps (like Shaco's boxes), and Stealth wards (the ones explained above) within their range. They also provide sight, just like a normal Stealth ward does. Whenever the enemy is in range of them (and in the same bush as them, if they are in a bush), he can see them. They can be destroyed with five auto-attacks from champions. They never expire. You can have one at a time on the map and carry two in your inventory. Use these visible wards to gain vision on invisible enemies or to clear enemy wards from important locations (such as Baron).
Farsight wards come from the blue warding trinket (available at level 9). This ward is different from the other two. It can be placed from very far away, granting you vision in a wide radius for a few seconds. However, enemies can see that you placed this ward for the first few seconds, even if they are far from it. Once the first few seconds pass, the ward's vision radius becomes short, shorter than that of a Stealth or Vision ward. These wards are visible to the enemy team, and can be destroyed with one auto-attack. They otherwise never expire, and you can have an unlimited number of them on the map.
Sweeper trinkets are another way the enemy can spot your Stealth wards and destroy them. They are the red trinkets from the shop. Running it over a location reveals all Stealth wards in that location. They also outline stealthed champions, but you cannot target these outlined champions for abilities.
As for the pink eye above champions, this is a short-duration buff which can be obtained from using Smite (summoner spell) on the Wraith Raptor camp (the jungle camp with four monsters in it). Smiting the big monster gives you a buff, indicated by a pink aura around the champion. As soon as you are spotted by a ward, be it Stealth, Vision, or Farsight, the buff expires, notifies you that you've been spotted, gives you the pink eye above your head, and allows you to see this ward for a short duration, during which you can attack it and destroy it.
Well, that was a lot of typing. Hope this helped you. Reply if you need any clarification, and remember that the LoL Wiki is your friend for this kind of information.
