Want to install Lutron Occupancy Sensor, but confused on current switch wiring
This looks like a MS-OPS2H-WH.
It doesn't require neutral so the wiring it simple.
For the two back wires that currently go to one terminal on the old switch, use a wire connector and twist those together with one of the black wires from the occupancy sensor (does not matter which one).
Connect the other black wire from the other old switch terminal to the remaining black wire from the new occupancy sensor.
Connect the green wire with the bare copper wire in the box.