Your insurance periods in Belgium are recognized in EU countries + EEA + Switzerland and vice versa (in accordance with general coordination rules) as well as in countries with which Belgium has bilateral agreements.
Belgium has bilateral agreements with:
Albania, Algeria, Argentina, Australia, Bosnia and Herzegovina, Brazil, Canada, Chili, India, Israel, Japan, Kosovo, FYR Macedonia, Moldova, Morocco, Montenegro, the Philippines, San Marino, Serbia, South Korea, Tunisia, Turkey, Uruguay and the United States of America.
Following the Agreement between the European Union and The United Kingdom of 30/12/2020, insurance periods completed in the United Kingdom are still taken into account after Brexit.
Your insurance periods are taken into account to check if you fulfill the requirements for taking up early retirement or for a more advantageous pension calculation, e.g. a minimum pension.