Entrails are the soft inside parts of a body, especially the long tubes that food moves through — the guts. People use it of animals more than of people, and often when a body is cut open: a hunter, a cook cleaning a fish, or a bloody story. It is a slightly old, bookish word; in a Taiwan kitchen you would more naturally name the part (liver, intestine) or just say 內臟. It is almost always plural. Though actually older stories talk of “reading the entrails” — guessing the future from an animal’s insides — so the word can feel dark and ceremonial, not only like cooking. You would not use it at a polite dinner to talk about food.