Is "sukne" genitive?
Not in this case. It's feminine accusative plural.
Why "pro dvacet dva holek"? Is it right? I would say "pro dvacet dvě holky" and "pro dvacet holek". Please can somebody explain to me this? Thank you
"pro dvacet dvě holky" is accepted, but it is not what a normal person would say, it sounds like some accounting report. "pro dvacet dva holek" is more natural. It is the same structure as pět holek, šest holek, sto holek, tisíc holek...