Isha is from the Sanskrit īśā (one who rules, goddess, protector) — feminine of Īśa (a name of Shiva). Isha Mohammed Sharaf — Yemeni-American figure. Princess Isha — modern Indian royal heritage naming.
Isha 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 Isha reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.