。
She still hasn't arrived.
Literal
[topic-は] still has-not-come.
来ていない is the negation of the resulting state of 来る ('come') — 'is not in the state of having come' = 'has not come [yet].' Compared to 来ない ('does not come') which is general, 来ていない specifically tracks the not-yet-arrived status as of now. まだ pairs with this negative resulting state to give the canonical 'still hasn't.' This is the kind of line you'd hear at a meeting where someone is overdue, or a host waiting at a door.