Other forms: oversees; overseeing; oversaw; overseen; overseed
To oversee is to supervise or watch over, the way a principal oversees a school or a store manager oversees everyone who works there.
This verb comes from the Old English oferseon, to "look down upon," which is also how oversee was originally used. You can say, "From this hill I oversee the whole town," but today it's much more common for oversee to mean supervise. If your Spanish club puts you in charge of the bake sale, you'll oversee everything: pricing the brownies, arranging cookies on a table, and reminding volunteers when to show up.