The turbine has a shaft attached to the magnet. When the turbine turns, the magnet turns, and an electric current flows in the coil and down any wire attached to it. Most electricity used in homes and industry is generated this way. Different kinds of electric power plants use different sources of energy to turn the turbine. Hydro plants use falling water to turn the turbine.
Wind turbines use wind to turn the turbine.
Other large power plants use steam to turn the turbine. They need energy from some source to boil water and create steam. Coal, oil, and natural gas are burned to boil water. Nuclear plants split atoms to get heat to boil water. Sunlight is focused by mirrors on water tanks to boil water.