Generally (in the US) the term convection oven is used to refer to an oven that forces hot air around with a fan, instead of an oven with the radiant heating elements.

Someone else commented that all ovens are convection and the correct term is “fan forced”… which might be technically correct, but that’s just not how the terminology is commonly used at least in the US. Some newer ovens have options clearly labeled “convection” that turn on a fan, sometimes in addition to the radiant heating elements.

The main reason I think people like convection ovens or air fryers is because the air circulation crisps the outside without overcooking the inside and without all the fatty oils required in a traditional deep fryer.