What part of speech is “fairly”

'fairly' can be used as adverb to express the degree to which something is done, or the level of intensity something is conducted.

1. 'She completed the project fairly quickly.'

2. 'He fairly excelled at the task.'

3. 'The job was fairly easy.'

be careful to not overuse the adverb 'fairly' as it can begin to lose its impact and weaken the strength of the statement.