From the 2011 video series, Museum of Obsolete Objects by Germany-based agency Jung von Matt, this is Morse Code. Consider Morse code a sort of texting invented over 130 years earlier than the invention of texting. Each letter is represented by combinations of dot and dashed tones, lights, or clicks, and to decode the full message, you need to recognize each letter’s combo. After you’ve watched it once, play it again with your eyes closed. Hear the patterns?
Bonus: it makes a great “secret” language. Here’s the entire alphabet: See and Hear Morse Code.
There’s also a handy chart here.