The phrase "to head out" means to leave a place or an event, usually indicating that one is going somewhere else. It can be used both as a phrasal verb and as an idiomatic expression. When used as a phrasal verb, it refers to the physical act of leaving, such as getting up from a chair or walking out of a room. When used as an idiomatic expression, "to head out" means to depart for another location, often with a specific destination in mind.