Oona is the anglicized Irish spelling of Úna — from the Old Irish uan ("lamb") or possibly the Latin una ("unity, oneness"). A revival vintage name with deep Irish heritage. Doctor Who (Avatar: The Way of Water sequels). Saint Una / Oona — early Irish saint. Una Stubbs — English actress (different spelling).
Oona 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 Oona reduce to 9, The Giver. This is a traditional interpretive system, not a factual claim about the name.