A vibraslap is a percussion instrument

Percussion instrument

A percussion instrument is any object which produces a sound when hit with an implement or when it is shaken, rubbed, scraped, or otherwise acted upon in a way that sets the object into vibration...

 consisting of a piece of stiff wire (bent in a U shape) connecting a wood ball to a hollow box of wood with metal “teeth” inside. The percussionist holds the metal wire in one hand and strikes the ball (usually against the palm of their other hand). The box acts as a resonating body for a metal mechanism placed inside with a number of loosely fastened pins or rivets that vibrate and rattle against the box.