When you see dry weight on a camper the dry weight on the campers weight sticker refers to the weight of the camper itself without fluids, cargo, passengers, or optional equipment.
When you add fluids such as water to the tank, sewer water or add any clothing, supplies, food etc then that adds some additional weight to the camper.
That then adds onto the amount of the dry weight of the camper.
Just like with a vehicle the dry weight of the vehicle would be the weight of the vehicle itself without gasoline, fuel, passengers or any other cargo.
So when you're pulling a camper you need to factor into the addition of any cargo, fluids, water etc that can add additional weight to the camper.
Make sure the vehicle is capable of towing the camper with the additional weight and also be able to stop safely.