Aces' refers to the number of serves that a player wins in a tennis match. It is considered a statistic that measures the serving ability of a player. 'ACES' is a term used in tennis to refer to the number of serves that a player wins in a match. It is a statistic that measures the serving ability of a player and is often used to compare players. ACES are an important part of the game and can be a deciding factor in the outcome of a match.