Adjectives describe nouns (people, places, things, ideas).
Here's an example:
* Popular music is often played on the radio.
In this sentence, "popular" describes the noun "music".
While "popular" is not a verb, it can be used to form verbs:
* Popularize - to make something popular
* Popularise (British spelling) - to make something popular
Let me know if you have any other words you'd like to check!