Here's why:
* Adverbs modify verbs, adjectives, or other adverbs. They tell us *how*, *when*, *where*, or *to what extent* something happens.
* Nouns are words that name people, places, things, or ideas.
Examples:
* Soon we will leave. (Adverb modifying the verb "leave")
* The future is soon. (Adverb modifying the adjective "future")
* I'll be there very soon. (Adverb modifying the adverb "very")
Let me know if you have any more questions!