Berlin and Brussels are in the same time zone. Both cities use Central European Time (CET/CEST). When it's noon in Berlin, it's also noon in Brussels.
Both cities observe daylight saving time, switching between CET (UTC+1) in winter and CEST (UTC+2) in summer.
Any time works! Since both cities are in the same time zone, scheduling calls is never a problem. Business hours are identical.
Berlin and Brussels are key EU cities - Berlin as Germany's capital and Brussels as the de facto EU capital. High-speed trains connect the cities in about 5-6 hours, and flights take about 1 hour.