Ace is a stroke in tennis in which the serving player wins a point. The ball hits the square. And then flies into touch. The host didn't have time to touch the ball. This indicator is being recorded and records are set.
It's like in a chess game: “checkmate.” I depicted this moment in the painting. When the ball touches the line, it hits the square and flies into touch without having time to touch the opponent's racket. That ball flies lightning fast and it's barely noticeable that it hits the line. But the submitter has a point.
It's important to win quickly and clearly, even if you're “leading” the game. Don't relax. After all, you can always win in one move.