In the Leagues menu you can see your current league placement, league wise, as opposed to the leaderboard where you see your placement compared to other players.

After winning PvP matches, you can come here to collect rewards after certain thresholds. The leagues are, in succession, Bronze, Silver, Gold, Diamond, Sapphire, and Elite Super Fucker.

Aside from the final rank, all the others have 6 steps each (VI to I).