Elettra is the Italian form of Electra — from the Greek ēlektron, meaning "amber" (the substance that gave us electricity through its electrical properties). In Greek tragedy, Elektra is the daughter of Agamemnon who avenged her father's murder.
Elettra 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 Elettra reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.