To saute is to cook food over high heat, usually in butter or oil. Many recipes begin by instructing you to saute onions and garlic in olive oil.
You can saute vegetables, meat, fish, or tofu. The quick, hot method of cooking browns the outer layer of food and keeps the inside flavorful. Sometimes saute is used as an adjective — you might buy your friend who loves to cook a fancy saute pan for his birthday. In French, the word sauté means "jumped" or "bounced," which also describes the way food jumps around the pan when you saute it.