This is the 2478th most frequent Japanese word.
働い
働い is not a complete word by itself. It is a conjugated form of 働く, which means "to work."
In this sentence, 働い is part of the verb 働く, conjugated into its te-form 働いて, suggesting an ongoing action of working.
彼は会社で働いています。
He is working at the company.
The word 働い is the base of 働いた, which is the past form of 働く, representing a completed action of working.
若い頃に一生懸命働いた。
I worked hard in my younger days.
Here, 働い comes from 働く, combined with the present continuous form 働いています to denote an ongoing action over time.