yourของเจ้า literally indicates possession, meaning “your” or “of yours.” In questions such as พูดอะไรของเจ้า and ทำอะไรของเจ้า, it can express annoyance or exasperation, like “what are you talking about?” or “what are you doing?” เจ้า is an archaic, literary, or fantasy-style form of “you/your.”