候教 is a polite, formal set phrase meaning 'await your instructions (or correction)' — used mostly in written or ceremonial contexts, such as the closing of a speech, a letter to a superior, or a reply to someone offering guidance. It conveys humility: the speaker positions themselves as a student or subordinate waiting to be taught. You won't hear it in casual conversation; it belongs to formal registers like academic lectures, business correspondence, or traditional etiquette.