The name Gianni is a girl's name meaning "God is gracious". Gianni and discussed in our forums with posts like "Boy and girl makeover with middles".
From the experts:
This Italian boys name has started to be used on girls, with over 50 girls in the US being given this appellation in 2015. Beware that the gender neutral names trend isn't international, and a female Gianni travelling through Europe is likely to be given a lot more grief. May we suggest the feminine Gianna or modern Giann as alternatives? For whatever gender, Gianni is one of the most popular Italian baby names around.