Frances is the English feminine of Francis — from the Late Latin Franciscus, meaning "Frenchman" or "free one." Saint Francis of Assisi (1181-1226) gave the masculine name worldwide currency; Saint Frances of Rome (1384-1440) the feminine.
Frances was hugely popular in the early 20th century — peaking at #6 in 1916. After a long decline it is returning. Today it sits in the U.S. top 500. Pope Francis has revived attention to Saint Francis's traditions.
Frances 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 Frances reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.