Robin is from the diminutive of Robert — Old Germanic hrod (fame) + beraht (bright) — and also the name of the red-breasted bird that since the Middle Ages has symbolized renewal and joy.
Subject of Roberts's memoir Everybody's Got Something (2014).
Robin 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 Robin reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.