Hello Morganic,
The nose weight for your car is the maximum permitted downward force the caravan hitch exerts on the cars towball when the car and caravan is stationary and on a level surface.
You must also check the caravan specification, which will have a nose load figure that can be different to the cars. You MUST not exceed the lower of the figures.
You can adjust the nose load by moving the position of objects inside the caravan. Object near the front of the caravan will produce a higher nose load, whilst moving them towards the rear of the caravan will reduce the nose load.
Aim to use the whole of the nose load allowance, as this aids stability whilst towing, but remember not to exceed the lower figure of the caravans or the cars allowance.