Not stupid at all. It is a dual voice guitar. So magnetic pickups and piezos in the bridge. Two jacks. One can use it with 1 or both jacks.
Those slits are for the active EQs (treb. mid, bass) and Vol on the piezos.
One knob handles master vol, the other master tone.
If using one jack, the middle knob controls balance between the magnetics andthe piezos. If using 2 jacks, that knob provides an additional piezo volume control.
The 5 way selects neck humbucker, neck single coil, both humbuckers, bridge singlecoil, bridge humbucker.