Marley comes from an English surname meaning "pleasant wood" or "marten meadow" — from Old English roots.
Marley entered the U.S. top 1000 as a girls' name in 1996 and has been climbing. Today it sits in the U.S. top 300.
Marley 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 Marley reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.