Hyolyn is from the Korean stage name hyo (효 — filial piety) + rin (린 — beautiful jade). solo: Dally (2018) + See Sea (2020).
Hyolyn 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 Hyolyn reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.