IPA: /fʊlˈfɪlmənt/
KK: /fəlˈfɪlmənt/
The act of completing a desire, promise, or requirement, often involving the delivery of goods or services.
Her fulfillment of the project requirements impressed the entire team.
Fulfillment is formed from "full" (from Old English *full*, meaning complete or filled) and "-ment" (a suffix used to form nouns indicating an action or resulting state). The word "fulfillment" means the state of being filled or completed, often in the context of achieving a goal or desire.
Think of being 'complete' or 'filled' ('full') and the state of that completion ('-ment') — that's what fulfillment means.