Here's why:
* Adjectives describe nouns. For example, "the golden sun" - "golden" describes the noun "sun".
* Nouns are things or concepts. For example, "sun", "chair", "love".
* Verbs are actions or states of being. For example, "run", "eat", "be", "sleep".
While "golden" can be used in a figurative way, it's still acting as an adjective in those instances. For example, "He has a golden heart" - "golden" is describing the quality of the heart.