Isabella is the Italian and Spanish form of Elizabeth — ultimately from the Hebrew Elīšeḇaʿ, meaning "God is my oath" or "pledged to God." The name developed in medieval Iberia and Italy, with Isabel as the Spanish short form.
The name has been in the U.S.
In Pythagorean numerology the letters of Isabella reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.