Explanation
Scenario: The app must be able to run both online and offline. If the mobile device on which the app runs is connected to the internet, the app must immediately submit the status report.
When data is submitted offline, the data must be stored in the app until the app is back online.
Mobile users often need to be productive even when they have limited or no connectivity.
LoadData and SaveData combine to form a simple mechanism to store small amounts of data on a local device. By using these functions, you can add simple offline capabilities to your app.
The SaveData function stores a collection for later use under a name.
The LoadData function reloads a collection by name that was previously saved with SaveData. You can't use this function to load a collection from another source.
Reference:
https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/functions/function-savedata-loaddata