Eos (Ἠώς) is the Greek goddess of the dawn — the daughter of the Titan Hyperion, sister of Helios (the sun) and Selene (the moon).
Eos as a girl's name is rare but rising as part of the broader return of classical Greek mythological names.
Eos 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 Eos reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.