HFC means hydrofluorocarbons. They're used as replacements (in air conditioners, refrigerators, etc.) for CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons) which deplete the ozone layer.
HFCs don't deplete the ozone layer, but they're also extremely potent greenhouse gases, and thus they're being phased out in favour of HFOs (hydrofluoroolefins), which neither deplete the ozone layer nor contribute meaningfully to global warming.