。
She has a sharp head for business.
Literal
She [topic-は] sharp business-talent [genitive-の] possessor is.
商才 ('business talent') is a Sino-Japanese compound from 商 ('commerce / trade') and 才 ('ability / talent'); the same 才 morpheme appears in 才能, 天才 ('genius'), and 文才 ('literary talent'). 鋭い ('sharp / keen') applied to an abstract quality means perceptive or astute — a sharpness of judgment, not of edge. The Xの持ち主 frame attributes the quality to the person, with a faintly elevated tone suited to characterization. The plain copula だ keeps the register casual — the same idea in formal speech would read 商才の持ち主です.