How many live wires are there in four-core cable and five-core cable? What color is the grounding wire? How to connect the wires?

Four-core cable and five-core cable only have three live wires, because they are all three-phase.

Grounding is usually black. If you have such a jack here, just plug it in directly, or it is for lighting, and the ground wire is connected in the distribution cabinet before it is led out. If there are three jacks, three-phase electrical appliances should not be connected to the neutral wire, because the load is balanced and the ground wire has a special jack. Otherwise, if you want to prevent leakage, connect one end of the ground wire to the shell and the other end to the ground.