"Are you French or Spanish?"
Translation:Te francia vagy, vagy spanyol?
Francia and spanyol are already adjectives (which can be used as nouns as well), but amerika isn't. Amerika is the name of the continent (or the country), so you'll have to make it into an adjective first with the -i suffix to use it like that.
The name of the countries of France and Spain are Fraciaország and Spanyolország, respectively, with ország meaning 'country'.
It's true that "francia" is the odd-one-out by being an adjective. Normally, for country names that end with '-ia' in Hungarian, the adjective has been formed by removing '-ia:' Anglia-angol, Hollandia-holland, Dánia-dán... as well as for most of Hungary's neighboring nations. Regarding the shift of "francia" from noun to adjective, it may have something to do with the fact that "Mi a franc?" means "What the heck?"
At one point is history, mentioning the French put Hungarians in a really bad mood.