Jyotsna is from the Sanskrit ज्योत्स्ना (Jyotsnā — moonlight, moonlit night) — from Sanskrit jyotis (light). Jyotsna is one of the Sanskrit feminine names — central to traditional Hindu poetic heritage.
Jyotsna 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 Jyotsna reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.