。
She has an innate aptitude for art.
Literal
She [topic-は] by-nature artistic talent [object-を] has.
芸術的な素質 means 'artistic aptitude/talent' — 芸術的 (artistic) + 素質 (aptitude, innate quality). 持っている means 'possesses.' 素質 (そしつ) specifically refers to raw, inborn potential — different from 才能 (さいのう, talent) or 能力 (のうりょく, ability), which can be developed.