Hi Larry and Michelle,
Welcome to the Heartland Owners Forum.
If this is the kitchen refrigerator, as opposed to a small outside refrigerator, then it runs on 120V AC. The 120V is supplied by either shore power, or by your batteries while towing or boon docking. There is a small inverter, dedicated to the refrigerator, that converts the battery power to 120V AC. From the inverter, it goes to a small transfer switch, also dedicated to the refrigerator. When shore power is available, the transfer switch uses shore power. When not available, the transfer switch uses the inverter output if the inverter has been turned ON.
If you're towing all day, the charge flowing from the truck will help to offset power used by the refrigerator. If you have an overnight stop without power, you can expect the refrigerator to run overnight without completely discharging your RV batteries. For longer stays with no shore power, you'll need to recharge the batteries with a generator, or solar installation.
You can read all about this in our owner-written
Residential Refrigerator user guide.