Gittel (גיטל) is the Yiddish diminutive of gut, meaning "good" — by extension "good one" or "the good little one."
Gittel was a common Ashkenazi name. Many American women named Gertrude or Gladys had the Yiddish name Gittel.
Gittel 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 Gittel reduce to 1, The Leader. This is a traditional interpretive system, not a factual claim about the name.