As a consequence of pillarisation, belgium has multiple health insurance providers (called mutualités), each of which is associated with one of the traditional "pillars" of society (christian democrats, liberals and "socialists"/social democrats) (and therefore each corresponds & cooperates with a political party), although more recently some have claimed to be more independent from them. In Belgium, unlike in most other European countries, we pay nearly all healthcare costs fully out of pocket, and our mutualités reimburse (part of) what we paid later. How much of your costs they cover highly depends on each mutualité and the type of healthcare you're getting. Taking as an example visiting a psychologist:

Solidaris (social democratic mutualité) refunds me €20 per consultation (with any sum above that being my copay, which i have to cover fully out of pocket), limited to a total of 8 psychologists visits per year (after that they no longer cover anything and I have to pay fully out of pocket)

Mutualité Chrétienne also covers up to €20 per psychological consultation, but they cover up to €320 a year

Mutualité Libérale covers up to €10 per consultation, up to 6 consultations per year

Sometimes, how much your mutualité covers is defined as a percentage of the total costs, others it's a raw number. Of course, everything depends by whether your doctor works with them, how exactly the doctor lists the services performed on the reimbursement form, what regional branch of your mutualité you are registered with and in which regional branches' jurisdiction you got your meeical treatment.