A lever makes work easier because it allows a person to move an object using less force. To reduce the force that is necessary to move the object, the person using the lever has to increase the distance for the area they are applying the force.
A lever rotates on a fulcrum, which is a fixed point. The lever is generally a rigid bar and the person moving the object has the object on one end of the lever and they use the other end to apply the force necessary to move it. The fulcrum goes between both of these points.