Return to Player (RTP) is a percentage that describes the total of all the winnings from a slot machine over a longer period of time compared to the total of all the players stakes. This is not calculated on a individual basis but on a general level. The RTP of a game takes into account all stakes by all players – no matter how big or small – over a very large period of time.
The RTP may vary from game-to-game but usually is within the range of 94 - 98% when talking about slot games. This percentage does not guarantee wins, all rounds played are entirely independent from each other. Meaning you may place several stakes in any game without getting any wins. Never gamble money you are not prepared to lose.
To find game specific RTP percentages, you'll have to locate the info panels or game instructions within the specific game. All the games specify their RTP in some form.
If you have trouble finding the RTP for a specific game, please contact Support for further assistance.