Can someone explain this relay pin drawing to me? It is a Releco C5-A30. Why are the contacts labeled twice, bold and not? Can someone explain how they'd wire this for just a simple N/O switch?
It's not a simple NO switch, it's a three pole dual throw relay switch.
As to the double numbering, the not bold numbers are European standard terminal markings where first digit is the pole, second is a contact codes 1 = common, 2 = NC and 4 = NO. The BOLD numbers are everybody else.
If you look at the socket for it, you will see the same markings.
If you WANT to wire it as a simple single pole NO relay, hook up your coil voltage across A & B, and use either pin pairs 4 & 7, 5 & 8 or 6 & 9 as your switch.