Yards After Catch is the term used in American football

American football

American football is a sport played between two teams of eleven with the objective of scoring points by advancing the ball into the opposing team's end zone. Known in the United States simply as football, it may also be referred to informally as gridiron football. The ball can be advanced by...

 for the distance gained by a receiver after catching a pass. Specifically, it is the forward yardage gained from the spot of the reception

Reception (American football)

In American football, a reception is part of a play in which a forward pass from behind the line of scrimmage is received by a player in bounds, who, after the catch, proceeds to either score a touchdown or be downed. Yards gained from the receiving play are credited to the player as receiving...

 until the receiver is downed, runs out of bounds, scores, or loses the ball. YAC is sometimes referred to as RAC for Run After Catch.

Its complement is Air Yards, the distance a pass travels forward of the line of scrimmage through the air until the spot of the reception.