Hi Alex,
His occupation is "gepasporteerd mineur", a miner (minelayer/sweeper) who has been discharged (with passport) after having completed his National Service. National Service normally lasted 5 years during which one was not allowed to get married without permission of your commander. It was quite common to run to the town hall after receiving your pass. The passport document itself would contain quite a bit of information about one's description, parents, campaigns, wounds, track record (good or bad) etc. Officially you were not really discharged but given indefinite and unpaid leave.
"Nagelmaker" is the surname of Theodorus Nagelmaker, whose profession is "borstelmakersknecht" (=brushmakers servant) and who is witness to the fact that Guillaume is insolvent and therefor not able to pay the legal fees involved with drawing up the documents necessary for a marriage.