A phrase used in basketball that refers to players on the team who are not actively participating in the game. It is also sometimes used to refer to players who never, or rarely, play. In the NBA, only five players from a given team may be on the court at one time. In order to not tire out players, teams often have at least one substitute player for every player who typically starts the game. The players not playing in the game will sit on the sidelines, sometimes on a bench.
The phrase "on the bench" comes from the typical seating style found on the sidelines of a basketball game. Although most sidelines now contain individual chairs, there was a time when there would only be a bench on the sideline for all players to sit on when they were not playing. Another phrase related to "on the bench" is "riding the pine", because benches were often made of wood and players who rarely played would be said to "ride" on the bench.