This is the 1435th most frequent French word.
rouge
Red.
Here, 'rouge' is used as an adjective to describe the color of the noun 'pomme' (apple).
La pomme est rouge.
The apple is red.
In this sentence, 'rouge' is used as a noun to denote the color red.
Le rouge est ma couleur préférée.
Red is my favorite color.
Here, 'rouge' is part of a compound noun 'rouge à lèvres', which translates to lipstick in English.