I really like this card and it's really cool to see some different spanish stamps, however for some reason they were not postmarked...
Since I already featured some info about Spain in another postcard, let's get into some vexillology (the study of flags).
The flag of Spain (colloquially known as "La Rojigualda"), as it is defined in the Spanish Constitution of 1978, consists of three horizontal stripes: red, yellow and red, the yellow stripe being twice the size of each red stripe. Traditionally, the middle stripe was defined by the more archaic term of gualda, and hence the popular name rojigualda (red-weld).
The origin of the current flag of Spain is the naval ensign of 1785, Pabellón de la Marina de Guerra under Charles III of Spain. It was chosen by Charles III himself among 12 different flags designed by Antonio Valdés y Bazán (all projected flags were presented in a drawing which is in the Naval Museum of Madrid). It was until 1843 that Queen Isabella II of Spain would make the flag official.
Throughout the 18th, 19th, and 20th centuries, the color scheme of the flag remained intact, with the exception of the Second Republic period (1931–1939); the only changes centered on the coat of arms.