。
She still hasn't gotten the hang of cooking.
Literal
[topic-は] not-yet cooking [genitive-の] knack [object-を] has-not-learned.
コツ ('knack, trick of the trade') is a versatile native Japanese noun for the small accumulated skills that come with practice — the 'feel' for something that you can only develop by doing. 覚える ('learn, memorize, get the hang of') with the negative resulting state ~ていない gives 'has not yet acquired' — Japanese frames 'knowing how' as a state arising from past learning, so the negation 覚えていない ('has not learned') means 'still doesn't know how.' まだ ('still, yet') paired with negative predicate is the canonical 'not yet' frame.