Colombia, Venezuela and Ecuador use yellow, blue and red as an homage to the flag of Great Colombia, the country that resulted after the independence of the Viceroyalty of New Granada and occupied the territories of the three countries, plus Panama.

Guatemala, El Salvador, Honduras and Nicaragua use blue and white as an homage to the flag of the Federal Republic of Central America, a country that included them plus Costa Rica, that also uses white and blue and a red stripe. Central America joined the First Mexican Empire in 1821 and declared independence after the fall of the Empire.

Argentina and Uruguay also share similar flags, both use blue and white and the Sol de Mayo (Sun of May). It is called "de Mayo" because the independence movement in the then Viceroyalty of River Plate began on May, 1812. This symbol has also appeared in previous Peruvian and Bolivian flags.

I do not, however, know what each colour means on those flags.

Arab nations use combinations of red, white, black and green. Those are known as the "Pan-Arab" colours. These are the colours of the flag of the Arab Revolt against the Ottoman Empire. Each color represents an Arabic dynasty, and are also said to represent a XIV century poem "White are our acts, black our battles, green our fields, and red our swords".