Are you asking the question "Are hydropower, wind power and photovoltaics the main forms of current renewable energy?" These three energy sources are currently the main forms of renewable energy.
Hydropower is a way of converting the kinetic energy of water flow into electrical energy. By building hydropower stations, the kinetic energy of water flow is converted into mechanical energy, and then the mechanical energy is converted into electrical energy through generators. Wind power is a way of converting wind energy into electrical energy.
Photovoltaics is a way of converting solar energy into electrical energy.