Note the article the Cana, and see on Joh 2:1. The article defines the Cana previously referred to.
Nobleman (βασιλικὸς)
Properly an adjective, meaning royal, from βασιλεὺς, king. It occurs in John only, here and Joh 4:49; and in all other passages is used as an adjective (Act 12:20, Act 12:21; Jam 2:8). Literally here, a king's officer. Wyc, little King.