"Variant of Ioannis"
The name Yianni is commonly a male name from the "Greek" origin.
Yianni is a transliteration of the Greek name Giannis (Γιάννης), the everyday form of Ioannis (Ιωάννης), which is the Greek form of John. The name goes back to the Hebrew Yochanan, conventionally glossed as "God is gracious." The Y spelling is a transliteration choice rather than a separate name: Giannis, Yiannis and Yianni all render the same Greek name.
Ioannis means "Traditional Greek name".
The pronunciation of Yianni is YAH-nee.