The French saying “tenir la jambe” means literally “to hold the leg.” What it means figuratively is “to hold someone back or to delay someone by saying lots of boring or irrelevant things to them.”

This conjures up images of trying to get away from someone who insists on telling you something, even though you have no interest in what they are saying.

The idiom dates to the start of the 20th century, so it is relatively recent, in French terms.

Equivalent English expressions include “to buttonhole someone,” or “to bend someone’s ear.”