Complex sentence: Thielmans was well liked for his modesty and kind demeanor in his native Belgium, and was known for describing himself as a Brussels "ket," which means "street kid" in old Brussels slang.
Split into simpler sentences: Thielmans was well liked for his modesty and kind demeanor. In his native Belgium, and was known for describing himself as a Brussels "ket," which means "street kid" in old Brussels slang.