Yeah so I will explain it really short here.
Look, Riot has a big space station just 50.000 miles above earth.
Inside that space station there are roughly 34.000.000 monkey sitting in front of ultra highspeed computers and pack players together into a game.
For example you're in queue now a monkey in the space station sees that you want to play a game. Now the monkey has a hard choice:
Who should the monkey choose to play with you.
He looks up your recent games and if you won a few recently, the monkey will pick bad performing players for your team and mix together 5 smurfs for the enemy team.
If you ever wonder why the queue time sometimes takes 5 - 10 minutes, that's because the monkey can't decide and has to ask his superior for further actions.
Hope I could help you out there.