In northern North America forced-air natural gas is pretty for single family homes. You have a gas furnace that blows heated air through ducts. It's supposed to be relatively inexpensive compared to electric baseboards, presuming you have all the natural gas infrastructure (or a big tank outside).
Same, I had to Google it too but didn't even understand the pictures since they were so alien.
Eventually found this page [1] which includes a basic description:
A baseboard heater is a convection heater. In such heaters, cold air coming in from a window enters the heater through a vent and hot air is dispersed through metal fins that are heated through electricity.
But it's still confusing because if it's cold outside (=you need heating) why would you have your window open to let in the cold air? That would also make your already-heated air escape ... duh.
Agreed, it's amazing how something that "feels" like it would get the same solution everywhere it's needed still does not, due to cultural differences, history, and stuff.