A sauté pan is a frying pan with straight sides. In French, it is actually called a “sautoir.”
A good sauté pan needs to be light enough so that you can toss things in it, if you want to use that technique while sautéing.
The straight sides are designed to help keep food in as you toss it, if you choose to.
Don’t overfill the pan, or the food will steam instead of searing. Sauté in batches if you have to.