This recipe means 3 ribs of celery. When a farmer pulls celery from the ground, it is in a stalk. Individual pieces broken off from the stalk are ribs. A stalk can have anywhere from 6 to 10 ribs on it. This error occurs in more magazines, websites, and cookbooks in recipes than I can count. It is probably the highest occurring error and the least known. Cookbook editors should catch this, but they don't. If you added, 3 stalks of celery to any recipe that is ALL you'd see and taste. Cooks unite. Pass this information along and perhaps magazines, websites, cookbooks, and more cooks will get this correct in recipes.