。
She's by no means a complete stranger.
Literal
She [topic-は] never see-not-know-not [possessive-の] person is-not.
見ず知らず ('total stranger,' literally 'without seeing, without knowing') is a fixed compound built from the classical negative ず on both verbs 見る ('see') and 知る ('know'). It survives mostly in this phrase and in similar fossilized expressions. As an attributive form, it takes の to modify 人: 見ず知らずの人 ('a complete stranger'). Compared to 知らない人 (everyday 'unknown person') or 見知らぬ人 (literary 'unknown person'), 見ず知らずの人 stresses the totality of the unfamiliarity: never seen, never known.