Rabia (رابعة) is the Arabic word for "fourth" — also commonly understood as "spring." Rabia al-Adawiyya (c. 717-801 CE) was the first female Sufi mystic, who taught the doctrine of pure divine love — loving God for God alone, not from fear of hell or hope of paradise.
Rabia is widely used in the Muslim world.
Rabia 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 Rabia reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.