You are not the car owner but at the end of the contract you can chose to either buy the car you drove by the market value or make a new lease with a brand-new model. To avoid unexpected costs, you should pay attention to the car return time at the end of the contract. A responsible car usage is expected.
The monthly price is calculated based on your choices. You can choose the car you want to drive (make & model, colour, …), the services you want to include, the contract duration and the mileage you expect to do. Car lease service use fixed interest rates, thus allowing you a superior predictability of the costs.