You getting expereience if: killed headshoted anyone 6 hurted enemy and he died of fall damage Anyone from leaderboard are in match Connected to server (1 time per day) Completed single player map (1 time per day)
Basically, you get experience by being active in-game both in SP and MP. It's basically a measurement on how "active" you are in playing the game. It also shows you on top of the "Most Active" Leaderboards.
Aaaaand, it's currently being used as a prize for PB2 Discord Events.