This is RCA male plug solder connector adapter, easy to connect audio video RCA cable.
The solder RCA male connector is widely used to connect to CD DVD player, phono, HDTV, speakers, stereo receiver, audio video av receiver, amplifier, tuner, home theater system, high fidelity HiFi system etc.
Center of the RCA plug should be connected to the positive, outer of the RCA plug should be connected to the negative.
Easy to handle, you really don't have to be a professional to do this. Insert the cables into the sleeve, solder the bare wire with the plug together, and then twist and lock in place.