Ha is from the Vietnamese Hà (river) or Hạ (summer). Ha is one of the Vietnamese feminine names — appears as standalone name or compound element in Hà Anh, Hà My, Hà Phương, and Thanh Hà.
Ha 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 Ha reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.