A conjunction meaning 'not only ... but (also) ...', indicating that something applies in addition to what was just mentioned.
彼は勉強ができるばかりでなく、スポーツも得意だ。
He is not only good at studying but also good at sports.
この本は子ども向けばかりでなく大人にも人気がある。
This book is popular not only with children but also with adults.
彼女は忙しいばかりでなく、いつも親切だ。
She is not only busy but is always kind.
価格ばかりでなく品質も重視してください。
Please value not only the price but also the quality.