"Finnish is a small but beautiful language."
Translation:Suomi on pieni mutta kaunis kieli.
I don't think I've come across with the expression "pieni kieli" in this sense though - sounds funny to me, as in buying a cow's tongue or something (which isn't exactly small). :D But I'm not saying it doesn't exist or that there wouldn't be some who use it.
I'd maybe rather use 'vähäinen' [minor] or something to express the fact that we're small in numbers (not to be confused with 'vähäpätöinen' [insignificant] in this case, though sometimes they can have some overlap in meaning). But that again is my personal preference. :)