。
She is wearing white clothes.
Literal
She [topic-は] white clothes [object-を] is-wearing.
Note 着る for 'wear' — Japanese uses different verbs depending on what's being worn. 着る is for shirts, dresses, coats, and other torso/full-body garments; pants and shoes use はく; hats use かぶる. ~ている here describes a state (currently in clothes) rather than the act of putting them on.