Technically, a heat pump is a mechanical-compression cycle refrigeration system that can be reversed to either heat or cool a controlled space. Or to put it a bit simpler; a heat pump is an air conditioner that can run backwards.
I am sure you have noticed when your a/c is on, if it is working properly, you will have cool or cold air coming out of the vents.
If you were to go to the outside part of your a/c you would find warm air coming from that. This is heat transfer, taking heat from one place to another.
So, in cooling it is taking heat from your home and putting it outside. Now in heating it is taking heat from outside and adds it to the heat from the compressor and brings it to the inside. This method of heating works very well in the southern states and cost way less in energy than electric heat.
So, let one of Spectrum Air Conditioning Comfort Consultants explain all the benefits of a heat pump, so that you can determine if this is the correct choice for your needs.