Mang nghĩa "làm lại cuộc đời, hành xử khác đi"
=If you say that you are going to turn over a new leaf, you mean that you are going to start to behave in a better or more acceptable way/to start behaving in a better way
IELTS TUTOR xét ví dụ:
He realized he was in the wrong and promised to turn over a new leaf.
Apparently he's turned over a new leaf and he's not smoking any more.
Tet Holiday symbolizes turning over a new leaf as it marks the transition from the old year to the new year in our lunar calendar