'知道啦' is an informal, spoken interjection meaning 'Got it!' or 'I know already!' It combines the verb 知道 (zhī dào, 'to know') with the sentence-final particle 啦 (lā), which conveys light impatience, playfulness, or mild exasperation—often signaling that the speaker has heard something repeatedly or finds the reminder unnecessary. Unlike neutral 知道, the addition of 啦 adds emotional color and interpersonal nuance, making it common in casual conversations among friends, family, or peers.

This phrase is typically used in response to instructions, reminders, or repeated information. It’s not rude by itself, but tone and context matter: said with a smile or chuckle, it’s affectionate; said sharply or with a sigh, it may suggest annoyance. It rarely appears in formal writing or professional settings, and never with superiors unless the relationship is extremely relaxed and mutually understood.