What does it meant to have an avulsion fracture of the cuboid bone?

A tendon injury: Sometimes, instead of a tendon tearing (a sprain) it pulls off the bone. It often takes a small piece of bone with it. This is called an avulsion fracture and is generally treated like a sprain.

Avulsion: An avulsion fracture means that a piece of the affected bone has been pulled off, usually by a tendon attached to that bone.