While this mechanic could literally mean rock-paper-scissors, a game that uses this game mechanic has a circular hierarchy for which pieces win against or capture others. For example, while A might beat B, and B beats C, C beats A. The name of this mechanic derives from the children’s game where Scissors cuts Paper, Paper covers Rock, and Rock crushes Scissors. But this mechanic can be used for any game with non-transitive mechanics.
Many of the more involved games that use this mechanic add several more variables like The Big Bang Theory adds more to Rock-Paper-Scissors. In addition to the original game mechanics of Rock-Paper-Scissors, Rock-Paper-Scissors-Lizard-Spock adds Spock smashes Scissors and vaporizes Rock, Lizard poisons Spock and eats Paper, but Rock crushes Lizard and Scissors decapitates Lizard, and Paper disproves Spock.