The red and yellow colors contained in the Spanish flag represent the colors of the original Spanish kingdoms. The Spanish flag also contains a coat of arms containing the Pillars of Hercules, which are meant to represent Gibraltar and Cueta.
Also contained within the coat of arms in the Spanish flag is the emblem of the House of Bourbon, which is the Spanish royal family. The emblem itself has a blue oval as well as three fleurs-de-lis encased in a border with a red edge. Inside of the pillars in the shield is a red scroll which reads, "Plus Ultra." Translated, this phrase means "there is more beyond."
The most recent version of the Spanish flag came into existence in 1981. There have been many variations throughout history, however the current version of the flag has roots to a 1785 flag, during Carlos II's rule of Spain. This is when the red and yellow colors of the flag were introduced, along with a purple stripe that was later removed. These colors represented the House of Bourbon during the reign of Carlos II. The current flag is similar to the flag of 1785, and the majority of changes made throughout the years involved the coat of arms.