Meaning of “act” - Learner’s Dictionary

act

verb uk us /ækt/
BEHAVE [ I ]

B1 to behave in a particular way:

Jeff's been acting strangely recently.
Stop acting like a child!
DO SOMETHING [ I ]

B2 to do something, especially in order to solve a problem:

We have to act now to stop the spread of this disease.
PERFORM [ I, T ]

B1 to perform in a play or film:

He's acted in a number of successful Hollywood films.

(Definition of “act verb” from the Cambridge Learner’s Dictionary © Cambridge University Press)