The answer to 'what does heat pump do' is a heat pump is a type of HVAC (heating, ventilation, and air conditioning) system that transfers heat from one place to another, rather than generating heat. Heat pumps work by moving heat from the outside air or ground into your home during the winter, and then reversing the process to cool your home in the summer.
Heat pumps are highly efficient and can provide both heating and cooling for your home. They work by using refrigerant to absorb heat from the outside air or ground and then transfer that heat indoors. In the summer, the process is reversed, and the heat pump removes heat from the indoor air and transfers it outside, providing cooling for your home.