Lucia is one of the most popular girl names in Spain, Italy, and across Latin America. In the U.S. it sits comfortably in the top 150 and is rising.
Lucia 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 Lucia reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.