Can someone please tell me what is the name of the device that clip on the metal terminal pieces for these wires (see picture) wires image thanks

That would be the connector body or plug body. The ends connected to the wires would be the contacts. It appears to be a standard .1" spacing to possibly fit a pin header, which is basically a row of equally spaced pins either directly attached to a PC board or the end of a cable. Some may or may not have a plastic body that is keyed to prevent incorrect connections.