professional; expert; reliable worker
Describes someone who is highly skilled at their job and performs it flawlessly. Often carries a nuance of dependability and mastery, sometimes used in a slightly dramatic or admiring tone.
He is a true professional. No matter how difficult the project, he always makes it succeed.
That craftsman is a real expert; the finish is perfect.
Compound of 仕事 (work, job) and 人 (person). The exact origin is uncertain, but it likely emerged as a colloquial term to praise someone's professional competence.