"a red robe" is called "une robe rouge" in French.
A red dress is 'une robe rouge' in French. Robe is a feminine noun.
Tu portais une robe rouge
Yes, "robe" is a feminine noun in French, meaning "dress." In French grammar, nouns are gendered, and "robe" is accompanied by feminine articles and adjectives. For example, you would say "la robe" to mean "the dress."
une robe rouge
robe blanche
belle robe
une robe (fem.)
robe noire
The word is garde-robe.
robe jaune
Translation: Ta garde-robe.
robe de mariee