noun
ball pit; ball pool
A play area filled with colorful plastic balls, commonly found in indoor playgrounds, family restaurants, and children's facilities.
子供たちはボールプールで楽しそうに遊んでいた。
The children were playing happily in the ball pit.
Variant with interpunct, sometimes seen in product names or signage.
Loanword from English 'ball pool' or 'ball pit', adapted into Japanese as ボールプール.