Gracious
Zianna is likely a modern elaboration of the name Anna or a variation of the Italian name Gianna. It combines the popular 'Z' prefix with the traditional Hebrew root meaning grace or favor.
Less common today
Zianna isn't in the latest US Top 1000. It last peaked at #3,891 in 2020.
US births per 5-year period, 1990βpresent (SSA data).