Definition
to take a leaf out of somebody else’s book : to behave or to do something in a way that someone else would
to take a leaf out of somebody else’s book : (人)の行動を手本にする、見習う
Example
I want to make more friends while learning another language. I’m gonna take a leave out of Anna’s book and join language exchange.
英語を話しながらもっとたくさんの友達を作りたいな。アンナを見習って言語交流に参加してみよう。