Learn Spanish Colors.

Colors are describing words (adjectives) and as any adjective in Spanish they can change their forms to distinguish between masculine and feminine, singular and plural.

Colors ending in "o" distinguish between masculine and feminine, singular and plural.

red in Spanish would be: rojo (masculine and singular)
roja (feminine and singular)
rojos (masculine and plural)
rojas (feminine and plural)

el coche rojo (the red car)
la falda roja (the red skirt)
los coches rojos (the red cars)
las faldas rojas (the red skirts)

The rest of colours will only distinguish between singular and plural.

el coche naranja (the orange car)
los coches naranjas (the orange cars)
la falda naranja (the orange skirt)
las faldas naranjas (the orange skirts)

Another important difference between English and Spanish when it comes to colors is the position they take with regards to the noun they go with. In English, the colors normally go before the noun and in Spanish they normally go after the noun.

I have a blue car. (tengo un coche azul)

Spanish Color Chart.