Hong (紅) is the Mandarin Chinese word for "red" — the color of joy, luck, and weddings in Chinese tradition. Also 鴻 (great swan, vast) or 虹 (rainbow).
Hong is widely used in China. Lady Hong (1735-1816) was the Korean Crown Princess who wrote the major memoir The Memoirs of Lady Hyegyeong.
Hong does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
In Pythagorean numerology the letters of Hong reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.