RV Generators are just what it sounds like, mobile power for your motorhome, 5th Wheel or camp trailer. They can run on gasoline, propane(LP) or diesel. They are specially designed and built with extra sound abatement and special mufflers to make them very quiet. Most motorhomes, 5th Wheels and some camp trailers come with a generator or are ready to have one installed. The compartment for the generator should have a label or notice stating how large of a generator you should purchase. You may want purchase one a little more powerful to make sure you don't pop a breaker when you decide to heat up that cup of coffee in the microwave.
You can also use a portable generator camping. If your RV didn't come with a special compartment for a generator to be installed then go with a portable. You just want to make sure to get the right generator for the job.
Even though most of the RV generators are very quiet some are louder than others and there are some State and National parks that have regulations on how loud(what decibel rating) your generator can be - You don't want to get asked to leave just after got all setup.