What Does "Peace on Earth" Mean?

I drive past a lot of places this time of year that have banners or signs that say "Peace on Earth/Good will to men." A lot of them are not places I would generally think of as being pro-peace as I conceive of peace. So, it makes me wonder what they mean by "peace." Is it just the absence of war? Is it a completely different kind of peace, something like "everyone now converts to my religion/worldview"? Is it something else or does it mean nothing at all? Is it just something said without thought at all? What do they mean by "peace"?