When someone outacts another person, they do something better or more impressively than the other person.
Outacting someone can be seen as a good thing because it means you are doing something better than someone else.
Examples:
She outacts her friend in singing.
He outacts everyone in running.
The cat outacts the dog in jumping.
The little girl outacts the big boy in math.
He outacts all the other players in the game.
The superhero outacts the villain in saving people.