。
She has big blue eyes.
Literal
She [topic-は] big blue eyes [object-を] is-doing.
目をしている is the [body-feature]+をしている construction for describing physical features — literally 'is doing big blue eyes,' idiomatically 'has big blue eyes.' The same pattern handles other inherent features: 黒い髪をしている ('has black hair'), 鋭い目をしている ('has sharp eyes'). It can sound odd to English ears but is the standard Japanese way of describing characteristic body parts. Note 大きな (irregular attributive of 大きい) here adds a slightly more lyrical or descriptive flavor than 大きい would.