Luna is the Latin word for the moon, and the name of the Roman goddess of the moon — counterpart to the Greek Selene.
Until recently Luna was rare as a given name in the English-speaking world — too literal, perhaps, or too associated with the moth. That changed in the 2000s.
By 2020 Luna had entered the U.S.
Luna 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 Luna reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.