Luz is from the Spanish Luz — light — referring to the Catholic devotion to Our Lady of Light (Nuestra Señora de la Luz). Luz is one of the Spanish feminine Marian-devotion names — central to traditional Spanish + Latin American Catholic heritage. 1722, Palermo Sicily). Spanish + Latin American feminine name.
Luz 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 Luz reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.