In Parasite (2019), Geun-se is the man living beyond the Park's house. He communicates with Morse code through the lamps above the stairs. In the last act, he uses this technique, but only the Park's son, Da-song, sees it from his tent in the garden. Being "fluent" in Morse code, he writes the message down and it is later briefly seen, but never addressed again.
Since I can't read Korean, my question is, what was Geun-se communicating and/or what did Da-song write down?