As a student in Brussels, if you want to live here, you will have to find a KOT.
Kot is the belgian name for the typical apartment in which you share the kitchen and bathroom with fellow students.
There are plenty of websites to help you find your temporary home.
If you are planning to study at Vrije Universiteit Brussel (campus Etterbeek) you have the option to live on campus.
There are single rooms availlable but you can also decide to share a room at U- Residence.
Students who are going to stay for one year can also try out the VUB Housing, but keep in mind that it is difficult to get in due to strict rules and deadlines.
Alternatively, there are many Facebook groups in which different people offer a place to stay. Before joining all these groups, read this article about "How to avoid house scammers".
During your first days in Brussels, while looking for a house, a hostel might be the best and cheapest solution for you. Furthermore, if you have an ESNcard you will have access to a 10% discount on your reservation in Hostelling International. You are welcome!