Plain English Meaning
Heating pads built into the leading edges of the wings, tail, or propeller that warm up using electricity to melt the grip of any ice that has formed, so the ice falls off.
Full Definition
A type of ice protection system in which electrical heating elements embedded in panels or 'boots' on the leading edges of wings, tail surfaces, or propellers warm the surface enough to break the bond between accumulated ice and the airframe, allowing aerodynamic forces or centrifugal force to shed the ice.