An adjective always modifies a noun.
Adjectives also function to indicate quantity:
Tip: In general, it's best to avoid vague adjectives of number (e.g. many, most, some) in academic writing. Rather, be exact regarding the number of the noun in question, and where appropriate, provide research as evidence. Doing so will make your writing more precise and demonstrates that you've done the appropriate research to support your statement. For example:
For more information regarding adjectives and how they differ from adverbs, please refer to The OWL at Purdue: Adjective or Adverb?