I used autocad in my environmental architecture class and basically it's a computer program that lets you view, create or share anything from blueprints for bridges and houses to schematics for computer chips or motors parts (I would use autodesk inventor for motor parts actually). Depends what kind of autocad class it is, but you can basically learn how to create things that i mentioned above

You usually use it to draw blueprints for machinists to manufacture parts with measurements and a given tolerance