Mabel comes from the Latin amabilis, meaning "lovable" or "loving." It was originally a short form of Amabel, a popular medieval English name.
Mabel was hugely popular in the late 19th century and the first decades of the 20th, peaking at #14 in 1891. After a long decline, it has returned strongly in the 2010s as part of the broader return of vintage names. Today it sits in the U.S. top 350 — Mabel and her cohort (Maeve, Hazel, Pearl, Iris) are firmly back.
Mabel 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 Mabel reduce to 6, The Nurturer. This is a traditional interpretive system, not a factual claim about the name.