What do the colors of the Spainish flag represent?

Answer 1

In the modern flag, the coat of arms are greatly simplified as compared to previous variants. Each of the four quadrants represent one of the four kingdoms that were merged to form a unified Spain at the end of the 15th century. Namely, the kingdoms are: Castile, represented by the castle, León, represented by the lion, Aragon, represented by the vertical alternating red and yellow stripes (four red stripes, five yellow stripes), and Navarre, represented by the linked chains. Also the moorish kingdom of Granada is represented by the pomegranate fruit in the bottom of the coat of arms. The two columns with the "plus ultra" ensign (meaning "further" in Latin) represent Spanish discovery and colonization of America, the columns being the mythological Pillars of Hercules (of the Strait of Gibraltar, gateway to the Atlantic Ocean). The "Plus Ultra" phrase replaced the former "Non Plus Ultra" (something like "No further from here") before the discovery of America, since Spain was considered "the Westernmost point" on Earth (thus, "no further from here".)


Much more at:
http://en.wikipedia.org/wiki/Spanish_Flag

Answer 2

red..for the blood to represent atrocities of the past
white..purity and their belief in Christianity
Green...not sure