In the rules of a game, you will often see ‘RTP’, which stands for ‘Return to Player’. The RTP is the payout percentage of the game, or the expected percentage of wagers that a given game will return to the player over a given period of time.
However, it is important to realize that the RTP is an average calculated over a very significant number of games, so not just when the game is being played.
RTP can vary greatly in either direction due to statistical variance, and varies from game to game.