A high-ranking person sits near the top of an organisation — government, army, police, a company. Ranking is the ladder of jobs from high to low. We almost always put it before a noun: a high-ranking official, high-ranking officers. It tells you about status in a hierarchy, not about being on TV. A high-ranking civil servant may be almost unknown to the public; a high-profile celebrity may hold no rank at all. The army and the civil service use it a lot; everyday talk might just say senior or top. High here is “up the ladder,” not tall and not expensive.