The total performance points is a value that determines a player's ranking position in comparison to others. It is calculated based on their achieved scores, the ppv2 algorithm and the weighting system.
The dedicated total performance points ranking for all players can be found on the global leaderboards. It can also be navigated to by hovering over the rankings menu on the website header and clicking the performance option.
A player's individual rank can also be seen from almost anywhere within the osu! game client interface.