Well that's not confusing at all, lol.

Here's my guess: the 4 conductor wire (black/white/red/ground) is coming from the breaker box (with everything disconnected the red/black wires would be hot with the breaker on) and the 3 conductor wire (black/white/ground) feeds the rest of the circuit.

You'd want to use the red wire (hot) to the brass screw and a pigtailed* white wire (neutral) connected to the other white wires to the silver screw. Pigtail* a ground wire with the other ones and put it on the green screw. The black (hot) wires don't need to be touched.

I would also wrap those ground wires up with electrical tape and/or cover the connections on the back of the new part because with those connections being open and the ground wires not being shielded there's a good chance of creating a short as you shove everything together when you're done.

*explanation video here

Edit: Didn't think about it being a switched outlet like the other post says. Haven't had to deal with those so feel free to ignore all but the last part about eliminating the possibility of a short.