In-game icon
Lift or Lifting is an action performed by pressing the appropriate button when available.
Mechanics[]
You have to be close enough to a 
Liftable Rock for this action to appear.
You must have the correct tool in your hand or the action will not appear. You will need either a
Stick or a
Sharpened Stick for the action to be available. You may have to Switch Hands with the tool for this action to appear.
You then have to press the appropriate button at the correct time for the lifting action to be successful. If you are unsuccessful, two things can happen: either you don't apply enough force and the rock doesn't move or you apply too much force and the item you are prying with is destroyed.