English Translation
He was a bookkeeper.
In the US, accountant and bookkeeper are two different jobs. When I look in the Larousse French dictionary, both are Comptable. I would not call an accountant a bookkeeper.
Bookkeeper is a much more basic job, recording daily transactions. Accountants analyze the bookkeeping. That is probably over-simplified. https://www.investopedia.com/articles/professionals/091715/career-advice-accounting-vs-bookkeeping.asp