The doctor decided that you should be hospitalized. This means that you have to stay in one of the hospital departments for the night. You will get a room, probably with a few other children who are being hospitalized.
Every child in the department has a bed with it all kinds of medical instruments next to it, some chairs, and a sofa bed, so mom or dad can sleep next to you at night. You can decorate your corner in the room to make it feel a like bit more like home.
In this section of the website you can see photos of rooms and departments, you can take a look at the departments' internal maps, and you can read about things you need to bring to the hospital (if hospitalization is planned), and about the daily routine at the hospital.