。
She is by no means an ordinary singer.
Literal
She [topic-は] never ordinary [of-の] singer is-not.
けっして~ない (here in kana, often written 決して~ない) is one of Japanese's strongest emphatic-negation pairs — けっして alone signals 'never, by no means' and demands a negative predicate. The double negative effect ('not at all an ordinary singer') is a backhanded compliment: she's not ordinary, meaning she's something more — extraordinary, distinctive, special. 並み ('average, ordinary, run-of-the-mill') is the casual workaday word for 'normal grade,' the same 並 that appears on sushi-shop menus where 並・上・特上 mark the lower, middle, and premium tiers of a dish.