Manasa (मनसा) is the Sanskrit word meaning "mind-born" or "born of the mind" — also the name of the serpent goddess of Bengal, daughter of Shiva, who grants fertility.
Manasa is widely used in India.
Manasa 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 Manasa reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.