To your edit, it should be 2 hots and a neutral is my understanding. Hots deliver electric and neutrals complete the circuit back to the back. In newer wiring the 4th is the ground but a 240v 3 wire has no ground. However, if it is a neutral it should be sheathed and individually insulated.
That being said, I’m not an electrician and most of this is just what I’ve learned from replacing outlets and rerunning 120v wire in this house. If an electrician wants to tell me I’m wrong I’m all ears