the Photoshop action is a recorded adjustments like levels,color balance,contrast,etc.. and you just press the play button and it will do all the recorded adjustments . and every action contains different adjustments which means different result you can find it here
open Photoshop
on the top panel find Windows > actions (or Alt + f9) you can create new group or new action
create new action and hit record
now every thing you do the action will record it ,when you finish hit stop (small square)
now you can hit play and the action will do all the adjustment that you have done ~
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