It is a tool for generating electricity using wind power.
It is based on the theory that as a magnet rotates in a coil it produces electricity.
A wind turbine is made up of basically a windmill, a coil (wire wrapped together) and magnet. The magnet is connected to the windmill in such a way that when the windmill spins the magnet spins also. The magnet is placed in a coil of wire(not touching it) so that when the magnet spins via the windmill, electricity is generated.
Hope this is what you wanted.