Marcia is the Latin feminine of Marcius. Marcia (1st c. BCE) was the Roman noblewoman, wife of Cato the Younger.
Marcia 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 Marcia reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.