Okay, so imagine you're playing a video game where you get points and rewards for doing well. In this particular game, there are twelve levels you can reach, kind of like climbing up a ladder.
Each level has its own set of challenges that you have to beat in order to move up to the next level. The challenges get harder and harder as you go up the levels, so it gets more and more challenging the higher you go.
Now, imagine all the players in the game are ranked based on how well they do. This means that if you do really well, you get a higher rank and if you don't do as well, you get a lower rank. Your rank shows how good you are compared to everyone else playing the game.
As you climb up the levels, you get more rewards and you unlock new things like weapons or skins for your character. And the higher your rank is, the better rewards you get. So it's like a big ladder where you climb up the levels and try to get a high rank to get better rewards.