For example, if you were connecting your Arduino (5V signals) to a module (3.3V signals), you would connect the “HV” pin on the module to the 5V supply pin on your Arduino and the “GND” pin near the “HV” pin to the “GND” pin on your Arduino. Also connect the lower voltage source to pin “LV” and its ground to pin “GND” near the “LV” pin.
Connect the higher voltage source to pin “HV” and its ground to pin “GND” near the “HV” pin. This module requires you to supply it with power from both the higher voltage level and the lower voltage level.