Answer:
This means changing your behavior in a positive way.
Step-by-step explanation:
The saying " turning to a new light" means the same way.
For an example a student has not been doing so well on his school work and his grades have been slipping. At one point he finishes an assignment and notices its a lot less stress doing the work right away instead of putting it off so far you can't finish it in time. So he changed his way or "turned over a new leaf" to doing well in school.
If you have any questions feel free to ask in the comments.