What does a lighted red arrow indicate?

A lighted red arrow signals that you must stop and wait. This indication applies to drivers intending to move in the direction the arrow is pointing; it explicitly prohibits any movement in that direction until the signal changes. The purpose of this signal is to control traffic flow and enhance safety at intersections, ensuring that vehicles must yield to any oncoming traffic or pedestrians before proceeding.

Considering the context of the other choices, the option suggesting you may proceed in the direction indicated would conflict with the requirement to stop. Similarly, the choice that permits a turn if it's safe is misleading, as a red arrow does not allow for turns at all. The option about proceeding with caution does not apply either, as the presence of a red arrow necessitates a complete stop, rather than a cautious approach to proceeding.