Turn over a new leaf 的意思是重新开始(改过自新,过新生活) 。

英文释义:means to get a new start ,to change everything about yourself .

例句：

Now let's turn over a new leaf.

现在咱们从头开始(建立较好关系)。

I'm turning a new leaf ,No more drinking ,No more smoking,It's a healthy life from now on.

我决定改过自新，戒掉烟酒，过健康的生活。