Pins 20 and 39 of the module under test have a physical connection to load resistors. This instruction connects the other terminal of these load resistors to one of three possible states: A power supply (VPWR), ground (GND), or open circuit. Comments are in green.

The Set_Loads function connects the loads specified in the parameters (J1-20:VPWR, J1-39:GND). In this case the load on pin J1-20 of the module is connected to the VPWR line and the load on pin J1-39 is connected to the GND line.