。
She has a sharp tongue.
Literal
She [topic-は] poison-tongue-specialist is.
毒舌家 (literally 'poison-tongue specialist') is a noun for someone known for caustic, biting speech. The ~家 suffix marks 'one who specializes in / is characterized by ~' — see also 評論家 ('critic'), 政治家 ('politician'), 漫画家 ('manga artist').