In American football what is play action?

I would guess that it’s anytime the ball is in play and the clock is advancing.

Merriam-Webster’s Collegiate Dictionary, 11th. ed. says “play-action pass… (1964) : a pass play in football in which the quarterback fakes a handoff before passing the ball – called also play=action”

Basically they execute a play that appears to be a run, but it’s fake, and the quarterback passes instead. The goal is for the defense to react to the run play thereby creating an opening for the receiver to catch the ball.

https://www.youtube.com/watch?v=ybfBBU2myok
https://www.youtube.com/watch?v=qBRey0o7rQQ