。
What's she like?
Literal
She [topic-は] what kind person is [question-か]?
どんな ('what kind of') is a true interrogative when it appears in main-clause questions — distinct from its universal-quantifier role with も or でも. どんな人 ('what kind of person') is the standard way to ask for a personality or character description, where English would say 'what's she like?' Note that asking どんな人 doesn't necessarily seek a comprehensive profile — it can be answered briefly with personality-trait words (優しい, 真面目, おもしろい etc.) or longer if a full picture is wanted.