Have a ball: have a wonderful time; really enjoy oneself
楽しむ、楽しい時間を過ごす

Noriko: How was the party last night?

Kate: Lovely. I truly had a ball.

ノリコ：昨夜のパーティーはどうだった？
ケイト：素晴らしかったわ。本当に楽しかった