Jahan is from the Persian jahān (جہاں — world). Her regnal title Nur Jahan (نور جہاں — Light of the World) was conferred by Jahangir in 1616. She was de facto co-regent of the Mughal Empire (1611-1627) — managing the imperial administration, farman (imperial decrees), and coinage bearing her name (the only Mughal empress to have coins issued in her name). She founded the Itimad-ud-Daula Tomb (Agra, 1626-1628) — architectural predecessor to the Taj Mahal — and was aunt of Mumtaz Mahal.
Jahan 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 Jahan reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.