A fan is something you hold in your hand, and you can wave it backwards and forwards to make a breeze of cool air over your face. This type of fan can be folded away so they are easy to store when you are not using them.
A fan is something with several blades that spin around when you turn it on. Fans are used to make a nice cool breeze when it is hot. Fans can also be used to suck air out of places like your kitchen or bathroom - this kind of fan is called an exhaust fan. Most electric fans have a cage around the blades so you do not hurt yourself or get your clothes caught on the blades.