Nash is from the Old English atten ash ("at the ash tree") — historically a male surname now crossing into feminine use. John Nash (1928-2015) — male; American mathematician; Nobel Prize in Economic Sciences (1994) for his work on game theory; his life was the subject of Ron Howard's A Beautiful Mind (2001) — winner of four Academy Awards including Best Picture, with Russell Crowe playing Nash; Nash was killed in a New Jersey taxi accident in 2015.
Nash 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 Nash reduce to 6, The Nurturer. This is a traditional interpretive system, not a factual claim about the name.