Joanna is the feminine of John — from the Hebrew Yochanan, meaning "God is gracious." In Luke 8:3, Joanna was the wife of Chuza (Herod's steward) and one of the women who supported Jesus from her own means.
Joanna 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 Joanna reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.