。
She's good at cooking.
Literal
She [topic-は] cooking [subject-が] skillful.
The most basic form: 料理がうまい. うまい is casual and can describe both food taste and skill — context makes the meaning clear. The more formal counterpart is 上手 (じょうず); both take が for the skill area, but うまい has a warmer, more colloquial feel.