The holes are for the fixing screws, that go though from PCB rear side.
If fixing screws are required, HIF3B*-**P-2.54W(88) is recommended.
It is nut built-in type that can be fixed with M2 screws from PCB rear side.
Screw length under screw neck is board thickness +4mm.
If it is longer, the screw may interfere with the lock movement.
* stands for series no.. ** stands for number of contacts.