Calla comes from the Greek kalós, meaning "beautiful" — and is the name of the calla lily, the elegant trumpet-shaped flower. The botanical Latin name is Zantedeschia; the common name Calla stuck from the Greek root.
Calla as a girl's name is rising — currently rare in the U.S. but distinctive.
Calla 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 Calla reduce to 2, The Peacemaker. This is a traditional interpretive system, not a factual claim about the name.