Complex sentence: A screw will usually have a "head" on one end that contains a specially formed shape that allows it to be turned, or "driven", with a tool and a tail, which allows the screw to penetrate the material.
Split into simpler sentences: A screw will usually have a "head" on one end that contains a specially formed shape that allows it to be turned, or "driven", with a tool. On the other end a screw has a tail, which allows the screw to penetrate the material.