Belgium organises higher education through separate language communities, and the admission rules, recognition procedures, and even the academic calendar differ between them. Applying to a Flemish institution and a French-community institution are genuinely different processes.
Establishing which system your target institution belongs to is therefore the first practical step, before any document is prepared.
Recognition and admission
Recognition of a Pakistani qualification is handled by community-level bodies and takes time. Some institutions handle it internally for their own admissions and some require the general equivalence procedure first.
This distinction changes your timeline by months, so confirm it explicitly rather than inferring it.
The visa file
Acceptance letter, proof of sufficient means for the stay, medical certificate, criminal record certificate for applicants over a certain age, health insurance, and legalised academic documents.
Means may be demonstrated through personal funds or a formal commitment from a sponsor using the prescribed undertaking, and the prescribed form matters.
After arrival
You will register with the local commune shortly after arrival to obtain your residence document. Communes vary in processing speed and in what they ask for, and the local requirement is the one that governs.
Belgium rewards applicants who are precise. Almost every difficulty in this corridor comes from treating a community-specific or commune-specific rule as a national one.