Aero is a relatively small continent and country, inhabited by all sorts of intelligent creatures. Pegasi make up roughly 50% of the population, with the remaining 50% split between earth ponies, unicorns, griffons, and others.
The majority of the population have wings, and so Aero's development and culture heavily revolves around the air and sky. It's common to see all manner of creatures flying around cities and towns, and there is no shortage of cloud cities dotted around the continent.
Technology in Aero is advanced, with Strato City in particular being heavily technological. Space travel was achieved not too long ago, the greatest accomplishment of the Aero Space Program so far being the Aero Space Hub, an orbital space station.