Ice-skating is sliding on ice in ice skates — the same action as to ice-skate, often named as a hobby or sport. You can ice-skate for fun, or you can watch people jump and spin in competitions (figure skating is one kind). The word looks like a verb ending in -ing, and it can work that way (“She is ice-skating”). Very often it is the name of the thing itself: “Ice-skating is popular in winter.” Same pattern as swimming or dancing. It is an everyday word. On signs and in adverts you will also see ice skating written as two words. Though actually, ice-skating and ice-skate are a pair: ice-skate is what you do in one moment; ice-skating is the doing, as a pastime or sport.