Cute Young Brunette Girl With French Braid Hairstyle Posing At The Signal Lamp

They have a secondary function as simple spotlights.
The idea of flashing dots and dashes from a lantern was first put in to practice by Captain, later Vice Admiral, Philip Colomb in 1867. His original code, which the Navy used for seven years, was not identical with Morse, but Morse code was eventually adopted with the addition of several special signals. Flashing lights were the second generation of signaling in the Royal Navy, after the flag signals most famously used to spread Nelson's rallying-cry before the Battle of Trafalgar.
The Commonwealth Navies and NATO forces use signal lamps when radio communications need to be silent or electronic "spoofing" is likely. Also, given the prevalence of night vision equipment in today's armed forces, signaling at night is usually done with lights that operate in the infrared (IR) spectrum making them less likely to be detected. All modern forces have followed suit due to technological advances in digital communications.