Subhadra was the sister of Krishna and Balarama in the Mahabharata — she eloped with Arjuna (with Krishna's approval) and bore his great son Abhimanyu, father of King Parikshit. In Jagannath temple traditions, she is worshipped alongside her brothers.
Featured in the Mahabharata and the Bhagavata Purana.
Subhadra 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 Subhadra reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.