RTP stands for Return To Player. This is the percentage, that is calculated for each game. It shows how much money on average you can get back if you bet 100 €. For example, if the RTP percentage is 94%, then on average you will return 94 € at a rate of one hundred €. The higher the percentage, the more chances a gambler has to win money. Of course, you should not rely entirely on this percentage, since it shows only the average value.