What does symbols on the USA flag mean?

There are 50 stars for each of the current states in the union, and 13 stripes which represent the original 13 colonies that became the first states

Colors: red for blood war and courage, white for purity, and blue for justice and freedom

US Flag Act in 1977: "The flag of the United States be the thirteen stripes, alternated with red and white and the union be thirteen stars, white in a bay of blue field that would represent a new Constellation"