ばかりでなく

The structure X + ばかりでなく + Y can be used to mean "not only X but also Y." It's rather similar to another structure we learned, which used だけ instead of ばかり. It's typically used in written language.

一生懸命勉強したら、日本語が上手になったばかりでなく、成績もよくなった。
When I studied Japanese as hard as I could, not only did my Japanese get good, but my grades improved as well.

リーさんはかっこいいばかりでなく、お金持ちだよね。
Lee-san is not only handsome, but also rich. (I'm having flashbacks here)

京都には日本国内からばかりでなく、世界中から観光客が来る。
Tourists come to Kyoto not only from inside Japan, but also from around the world.

お祭りに行った時、たこ焼きばかりでなく、焼き鳥も食べたんだ。
When we went to the festival, we ate not only takoyaki, but also yakitori.