Inverter…or converter?
Converter changes 120VAC shore power to 12VDC to charge
battery and run 12V equipment (lights, water pump, roof vent fan…) when you’re plugged it. Pretty much every RV has a converter.
Inverter changes 12VDC
battery power to 120VAC to run household appliances like a coffee maker or hair dryer when off-grid. Inverters are uncommon on smaller RVs, especially vintage units unless added by a recent owner. Inverters are often accompanied by larger battery(-ies) and
solar panel(s).