Mansa is from the Mande Mansa — king, emperor, sultan Mali Empire royal title also Akan feminine third-born daughter. Mansa is one of the Mande + Akan feminine + unisex names — central to traditional West African heritage. West African name reflecting Mande royal heritage.
Mansa 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 Mansa reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.