It stands for "Most valuable player" Its the player with most kills in the round. (Not in game, but rounds) Example: If you go to Line Dash, you'll see that there's 9 games. If you win or lose in a game, but you had the most kills, you'll get the "MVP". (It doesn't matter if you win or lose, its just the player with most kills).
Also, This is a question, not a suggestion. So please next time, try to post your threads into the correct place.
Thank you.
It is not a rank. It is simply a indicator to who scored the highest/killed the most players /captured most mobs. It does not give any special effects/advantages.
Just a little tip, you should probably ask questions in the Support section.