Translation:The flag of Norway is red, white and blue.
"Norway's flag" would be somewhat more common, I would say. Why does the Swedish question maker assume that English should use the "of" structure? Lack of experience with English? Too many second language speakers of English overuse the "noun of noun" structure in English.
Sorry if im replying to an old conversation, i can't see on mobile, but "The Flag of Norway" sounds super formal. Atleast here in America, 9 out of 10 times we would say "Norway's flag". "The flag of Norway" doesn't neccesarily sound 'wrong' but it's like what they would refer to it on the news or like in a newspaper article etc.