First off, please title your thread better next time
It has been edited.
The zero trigger system grants the user a lighter trigger pull but also adds higher internal efficiency when using a strong spring. When you put an extremely strong spring into a bolt action it creates an extreme amount of force when cocked, a force you have to somewhat fight through when pulling the trigger. The zero trigger mechanism relieves the user of this issue.
This is how I understand zero triggers at least, maybe someone else can add something.