"JP" in "Grand Theft Auto 5" is an abbreviation that means "Job Points." JPs are earned when a player completes a mission when playing the "GTA Online" mode of the game. The points are only used in playlists to determine the winner at the end.
When a player participates in a race in the GTA Online mode, the winner of the race earns 15 JPs. Any rank below the first earns three less JPs than the position above it.
"Grand Theft Auto 5" is an multi-platform game that was developed and released by Rockstar Games and its subsidiary, Rockstar North.