。
She's nothing more than a singer.
Literal
She [topic-は] singer [no-more-than-にすぎない].
~にすぎない is a useful diminishing pattern: N + にすぎない = 'is no more than N / is merely N.' The bare verb 過ぎる means 'exceed, go past'; in negative form attached to a noun via に it becomes 'doesn't go past being (just) N.' The connotation can be neutral-descriptive or dismissive depending on context, but the sentence is most often used to belittle or downplay — 'she's a singer and that's all she is.' In writing and formal speech the related ~に過ぎない (with kanji) is identical in meaning.