Caelia (also Celia) comes from the Latin caelum, meaning "heaven" or "sky." The Roman family name Caelius was used by various Roman senators.
Caelia is rare as a given name but distinctive — chosen by parents drawn to the Latin form rather than Celia.
Caelia 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 Caelia reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.