。
She has a flexible mind.
Literal
She [topic-は] flexible head [object-を] is-having.
柔軟な頭をしている (to have a flexible head/mind) uses the pattern [quality] + をしている to describe an inherent characteristic. 柔軟 (じゅうなん) means flexible or adaptable, and 頭 here means 'mind' rather than the physical head — much like 頭がいい (smart). The ~ている marks this as a persistent trait, not a temporary state.