120 volt outlets (like in your house) only work when you have an outside source of power, either a generator, or your "shore power" cord is plugged into an outlet in the campground, or at your house.
To have your outlets work when on batteries, you'll need an INVERTER (changes 12 volts DC to 120 volts AC). These devices will EAT battery life, and will only provide power to their rating - a 1000 watt inverter will only provide 1000 watts (think hair dryer), not provide enough power to turn on the microwave, AC, toaster, and the hair dryer.