A Provisioning package allows you to apply settings over an existing standard Windows IoT install. For instance you can use one to add certificates, set update times etc.
Resources
https://developer.microsoft.com/en-us/windows/iot/docs/management
All the items you can manage via a provisioning package
Creating a Provisioning Package
“Windows Image Configuration and Designer” is included as part of “Windows 10 Assessment and Deployment Kit (ADK)”, which can be downloaded from:
http://go.microsoft.com/fwlink/p/?LinkId=526740
Install it on a Windows 10 PC
Start > Programs > Windows Kits > Windows ADK > Windows Imaging & Configuration Designer
Create: Advanced provisioning > Give it a name and location > Select “Windows 10 IoT Core” > Finish
In the ‘View’ dropdown select “Common IoT settings”.
Now make the settings etc you require for the package.
Once complete select 'Export' from the toolbad and 'Provisioing package'.
To Install It
Copy the .ppkg file to C:\Windows\Provisioning\Packages directory on the IoT device. Upon reboot of the device the package will be executed.