Brooklyn comes from the New York borough — and the borough was named after the Dutch town of Breukelen, meaning "broken land" or "marshy land," reflecting the wet terrain of original colonial Brooklyn. The name is now far better known as a place name than as a geographic descriptor.
Brooklyn entered the U.S.
Brooklyn 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.
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In Pythagorean numerology the letters of Brooklyn reduce to 4, The Builder. This is a traditional interpretive system, not a factual claim about the name.