Nani is Hawaiian for "beautiful" or "splendid."
Nani Pelekai is Lilo's older sister and protector in Lilo & Stitch (2002).
Nani 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 Nani reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.