Well all generators with a few exceptions produce 120 volts. What will determine if a generator will run your air conditioner is the number of watts the generator will put out.
You need to learn the wattage needed by the air conditioner and also learn the max watts put out by the generator you have (Assuming you have one already) it the generator produces more watts that needed by the AC unit you are good to go.
Not on the other hand if the generator you have dose not produce enough watts or you do not have one then it is a matter of buying a generator with the wattage required by the AC unit in your camper.
Now if you are going to buy one I would also determine what else you would like to run from the generator (in addition to the air conditioner. Figure out the watts need by these items add them together with the watts needed by the AC unit. Then buy a generator big enough for your needs.