、。
Not only does she work hard, she's also charming.
Literal
[topic-は] hard works [not-only-だけでなく], attractive [explanatory-だ].
~だけでなく ('not only X but also') is the standard 'X plus' connector — the structure verb/clause + だけでなく + Y where Y is something additional and notable. It often pairs with も or also-flavored elements in the second clause for the 'also' meaning, but here the second clause is just a flat statement with the additive force coming from だけでなく itself. 魅力的 is a Sino-Japanese な-adjective ('charming, attractive') with the suffix ~的 productively turning nouns into adjectives.