Amna is from the Urdu / Arabic آمنہ (Āmina — peaceful, safe, secure). Amna is one of the Pakistani Urdu + Arabic feminine names — central to traditional Pakistani-Muslim heritage.
Amna 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 Amna reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.