忽必烈 is the Chinese name for Kublai Khan, the fifth Great Khan of the Mongol Empire and the founder of the Yuan dynasty (1271–1368). As a historical figure name, it's a proper noun with no grammatical variation — you use it like any personal name in Chinese, typically as the subject or object of a sentence. The name is trisyllabic (Hū-bì-liè) and each character is pronounced with its full tone.