The flag of our nation is red with a part of blue and a white sun.Red represents the people's livelihood and fraternity, moreover, it means "One for all, all for one" and signifies the blood of the revolutionaries who sacrificed themselve.Blue represents nationalism and liberty.White represents democracy and equality.Besides, in Chinese culture red symbolizes lucky or love, it usually appears in the celebrations.Because of the sky and ocean, blue symbolizes liberty or peace, and it also represents the male.White often means positive things like purity and honesty.And that is why doctors and angel is white appearances. この表現は自然ですか？

The flag of our nation is red with a TAINT of blue and a white sun.Red represents the people's livelihood and fraternity. Moreover, it means "One for all, AND all for one", and signifies the blood of the revolutionaries who sacrificed themselveS. Blue represents nationalism and liberty. White represents democracy and equality. Besides, in Chinese culture, red symbolizes luck or love, AND usually appears in celebrations. Because of the sky and ocean, blue symbolizes liberty or peace, and it also represents the male. White often means positive things like purity and honesty.And that is why doctors and angelS ARE CLAD IN WHITE.

very good overall!
It's by no means a mistake, but I would have used 'camaraderie' instead of 'fraternity' (since the latter is often associated with male-only societies, clubs, or organizations)