Pliers are an example of a lever. The handles are longer than the jaws of the pliers. When pivoted around the joint, the force on the handles is multiplied in proportion to exert more force to objects in the jaws.
Not only do you use pliers to grab things, but also to rotate them. If the object you are grabbing is a bolt, the pliers also act as a lever when you use them to rotate the bolt. Pliers act as a lever when they grab onto things and also when they are used to rotate things.