Protection was any method of keeping people safe from harm or abduction.
In 2266, James T. Kirk offered to teach Charlie how to fight in the ship's gymnasium. He then demonstrated a shoulder roll. After watching Kirk execute the move, the boy refused to try the maneuver himself, and Kirk ended the lesson. Evans promptly protested, but Kirk explained that "you have to learn to protect yourself in a fall first. It's more than teaching you to defend yourself." (TOS: "Charlie X")