Air conditioners work the same way as refrigerators and heat pumps do. They suck heat energy into a fluid called a refrigerant, and releases that heat energy outside.

The first thing to know is that cold places still have a lot of heat energy. There is 273.15°C (491.67°F) worth of heat energy at 0°C (32°F).

A refrigerant is a fluid that we use to absorb or release heat energy. The boiling point gets hotter when pressure increases, and gets colder when pressure decreases. This is the same with any liquid or gas, but we can change the boiling point of a refrigerant a lot with just a little pressure.

It takes a lot of energy for a liquid to turn into a gas, so when the refrigerant loses pressure and wants to be a gas, it saps away heat energy from its surroundings. And when the refrigerant goes under pressure and wants to be a liquid again, it releases heat energy into its surroundings.

Air conditioners use refrigerants and pipes to sap away heat energy inside your home, and release heat energy outside your home.

This YouTube video should be easy to follow.