I’m afraid I’m not familiar with Strat wiring, but both of those black wires go tot eh chassis of the pot, so they’re both ground. I would imagine that one goes to the output jack ground, and the other to bridge ground. The red one connected to the left side lug of the volume put would be the input from the switch, and the yellow one connected to the middle lug would be the output to the jack.

Please take all that as a (barely) educated guess though. As I say, I haven’t wired a strat.