If a spray, a fridge, or another product is ozone-friendly, it does not put out the old chemicals (CFCs and the like) that eat away at the ozone layer high above the Earth — the layer that helps shield us from strong sun. The label was everywhere in the late 1980s and 1990s, when countries were banning those chemicals. It is a bit dated now, because the worst of those chemicals are mostly gone from shops, but you will still meet the word. It is everyday packaging language, not lab language. Though actually, ozone down at street level (in smog) is a different problem; ozone-friendly is only about that high layer.