The Emperor is four, worldly order; the Hierophant is five, the order of spirit and knowledge. He sits between two pillars like the High Priestess, but the veil is gone, two students kneel before him, his hand is raised in blessing — the knowledge she held is, with him, taught. In the minors five breaks things; in the majors it joins the individual to something larger than himself: tradition, institution, lineage.
Where you'll recognise it: seeking a teacher, entering a group with rules, learning a craft that has an established path, and the phases of 'do it their way first, ask questions later'. This card is about accepting a form that's been handed down, because there are things in the form you couldn't have thought of alone.
Running well, the Hierophant is the most grounded kind of learning: guided, on a path, no reinventing. Stuck, his problem is form eating content — following the rule and forgetting why, treating authority as truth, or the reverse: rejecting everything the institution preserved because you dislike the institution. The two students kneel temporarily. Once they've learned, they're meant to stand — that's part of the tradition too.