SOS doesn’t stand for anything. People made it up later.
The original distress signal was CQD, which stood for “seeking you, distress” or “all stations, distress,” according to PBS. This was widely used by the British, while Germans used SOE and the Americans used NC, which meant “call for help without delay.”
A 1906 International Telegraphic Radio Conference effectively standardized communication by suggesting the simpler SOS, which is easier to signal because of its distinct dots and dashes sequence.