Rocket League is a game about football and cars mixed together all you have to do is get the most goals to get XP to level up.You can also costomise your car,to get customisation options you can buy keys to open crates that you can get in the game you can get skins from crates and trades with other online players to get the skins you like.In Rocket League in any mode you can play with your friends.
Competitive Rocket League is a mode where you need to try and get to the highest rank there are 7 ranks each of them have 3 different tiers for example Bronze1 Bronze 2 Bronze 3(Silver Gold ECT).
Casual is the other mode opesite to competitive casual is where you can play with other online players to practise or mess about and have fun.
Training is a mode where you can practise on your own and learn newmoves. There is also a custom training where other players have set up a training set where you can try out other players custom made training arena.