LoL is nothing like Metin2/WoW etc. It's a whole new concept. You got an account which you can lvl up by winning games against bots or real players. In each game you can select a hero (there are always a few free to play) and play with him. You start on a map with two bases, which are connected with three ways. On each way are some towers which need to be destroyed first. But the main aspect is that you have to fight against other players, who also play a hero (mostly it's 5v5).
Kinda hard to explain but it got nothing of an MMORPG (like WoW, Metin2 etc)