im pretty sure our national identities are national symbols, language, colours, nation’s history, blood ties, culture, music, cuisine/food. all of these thing make up a nation, symbols could be what exactly the nation puts on a flag, what i mean by that is, sometimes nations put there national bird or flower on their flag because it means something to that nation, same with colour, colours could have national importance to a nation because they have some tie to it. hope this helps!!