。
She has a negative attitude toward life.
Literal
She [topic-は] life [toward-に対して] negative attitude [object-を] is-taking.
The compound particle に対して marks the target of her attitude, emphasizing directionality more than a plain に would. The collocation 態度をとる ('to take/adopt an attitude') is the standard Japanese way to express someone's stance — とる here doesn't mean 'to take' physically but 'to assume' or 'to adopt.' The na-adjective 否定的 uses the productive ~的 suffix to turn the noun 否定 ('negation, denial') into an adjective.