Here's the breakdown:
* Punch: In boxing, a punch is a direct hit with the fist.
* Pulling a punch: This refers to a boxer deliberately hitting their opponent with less force than they could, often as a gesture of sportsmanship or to protect the opponent from serious injury.
* Pulling no punches: This means hitting with full force, without holding back.
Therefore, the idiom "pull no punches" means to be completely honest and direct, without holding back criticism or negative opinions. It implies a frank and forceful approach to communication, often used in the context of criticism or confrontation.