Parts of speech

An adverb is "a word which describes or gives more information about a verb, adjective, adverb or phrase:

• In the phrase 'she smiled cheerfully', the word 'cheerfully' is an adverb.
• In the phrase 'the house was spotlessly clean', the word 'spotlessly' is an adverb." (Cambridge University Press, n.d., para. 1)

For more information regarding adverbs, adjectives, and the differences between them, please refer to The OWL at Purdue: Adjective or Adverb?

Reference

Cambridge University Press. (n.d.). Adverb. Cambridge dictionary. Retrieved February 24, 2021, from https://dictionary.cambridge.org/dictionary/english/adverb