Glossary
The maximum trailer weight is a limitation on the maximum weight of the trailer and load, which depends on the design of the car and the coupling device (gross weight determines). The maximum trailer weight for your particular car is stated in the car's registration certificate under the item O.
Also keep in mind that with a regular B driving licence, you can tow a trailer that weighs a maximum of 750 kg, or heavier trailers as long as the trailer and the car's total weight do not exceed 3,500 kg. This is regardless of whether your car is technically capable of towing heavier trailers.