The flag that is commonly associated with Black History month is the Pan-African flag, featuring red, black and green stripes. It was was created in 1920 by Marcus Garvey to symbolize the unity of and liberation of people of Africa descent worldwide; the colors represent the blood shed in the fight for freedom (red), the black people themselves (black), and the rich of land of Africa (green). The significance is widely adopted by black communities to celebrate their shared heritage and fight for equality.

Sources : https://www.gsa.gov/about-us/gsa-regions/region-8-rocky-mountain/region-8-newsroom/rocky-mountain-region-feature-stories-and-news-releases/a-historic-flag-raising-during-black-history-month-02152023