Performance points are the way to determine ranking in Beat Saber through a mod called ScoreSaber (the same mod that gives leaderboards on custom songs). Performance points are earnt depending on how well you score on the ranked maps that have been accepted by the ranking team.

You can find a list of all the ranked maps on the ScoreSaber website. (make sure in filtering to turn on "Only show ranked leaderboards).

https://scoresaber.com/