Della is the English diminutive of names ending in -della (such as Adella, Cordelia) or of Delia — also from the Germanic edel (noble). Della Goodwin — American educator. Della Reese was inducted into the Hollywood Walk of Fame (1994). Della is also the diminutive of Adele.
Della 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 Della reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.