RTP stands for Return To Player.
The RTP percentage is a measure of the percentage of stakes a game returns to players (generally over a minimum of one million plays), and is a generally accepted guide to how a game will perform.
If a game has a stated RTP of 92%, it generally means players can expect the game to return £0.92 in the £1.00 (or currency equivalent) over a long period of plays.
The game must perform to the RTP as stated in the applicable Game Rules.
However, this does not mean that every play or series of plays will return this percentage. Individual players should understand that as wins are awarded randomly, then the return to them individually may not equate to the advertised RTP. They can expect a return in a range between nought and the maximum prize level for each individual play.
Random games are not 'compensated', so just because there has been a series of losing plays it does not mean that this will be followed by a series of winning plays. The outcome of one bet does not affect any other. The game is random and therefore players should only ever stake what they can afford.
All games are slightly different in terms of their characteristics and feature sets and accordingly, they all behave slightly differently.