Translation:He seems to have finished his work.
"Work" and "job" don't necessarily have the same meaning, and often aren't used the same way. If you said "He seems to have finished his job", I wouldn't really understand what you meant. But if you said "He seems to have finished the job", then I would understand - he's finished whatever task he had to do.
It is the past infinitive ("Infinitif passé"). See https://www.lawlessfrench.com/grammar/past-infinitive/ or https://www.thoughtco.com/french-past-infinitive-1368898