。
She's certainly not the angelic type.
Literal
She [topic-は] never angel [like-のような] person is-not.
The simile-builder ~のような ('like X, similar to X') turns 天使 ('angel') into a modifier for 人, so 天使のような人 = 'a person like an angel.' This noun + のような pattern is the standard way to say 'X-like'; the same template generates 子供のような大人 ('a childlike adult'), 夢のような話 ('a dreamlike story'). 決して~ない then rules the whole 天使のような人 description out for her — denying not the noun (人) but the modifying simile (angelic). The result is a pointed, perhaps slightly tart character sketch.