Proper 5vdc relay module hookup
you should switch the live wire, not neutral or ground, switching neutral makes more of the circuit live which reduces safety.

The relay is intended to switch AC, it may be suitable for DC but the maker hasn't marked that on the case of the relay. if you can find the datasheet for this relay it will say if it can switch DC reliably.

Do a search on "JQC-3ff" datasheet