The V++ side is connected to the higher voltage circuit. Jumper 2, Pin 1 VCC, Jumper 2, Pin 2 signal.
The V+ side is connected to the lower voltage circuit. Jumper 1, Pin 1 VCC, Jumper 1, Pin 2 signal.
Jumper EN can either be closed to enable the TwoWayLevelShifter permanently. Or connect Jumper EN, Pin 1 to logical hight ( max V+ ) to enable or logical low to disable.