Charity comes from the Old French charite, from the Latin caritas, meaning "Christian love" or "generosity to the needy." It is the third theological virtue alongside Faith and Hope (1 Corinthians 13).
Charity has been used in English since the medieval period as a virtue name, becoming popular among Puritans in the 17th century. Today it sits in the U.S.
Charity 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 Charity reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.