Many words in English can have more than one job, or be more than one part of speech. For example:

1. 'work' as noun : My work is easy. / 'work' as verb : I work in London.
2. 'but' as conjunction : John came but Mary didn't come. / 'but' as preposition : Everyone came but Mary.
3. 'afternoon' as noun : We ate in the afternoon. / 'afternoon' as adjective We had afternoon tea.
4. 'well' as adjective : Are you well? / 'well' as adverb : She speaks well. / 'well' as interjection : Well! That's expensive!