Before, reading this KB article you may want to first see https://www.2brightsparks.com/resources/articles/restore-from-versions.html
Restore or Rollback is used to revert your Source/Destination file to a previous version created during earlier profile runs.
If you want to restore a small set of files from version files, then use the 'Restore' option. But if you have many files to restore, then perform a 'Rollback' operation to rollback the files to a specific date.
You can Rollback/Restore your version files only when 'Versioning' is enabled and version files exist.
This article explains the Restore/Rollback process using the Versioned files created on the Destination side (for a Backup or Mirror Profile):
Step 1: Run the Profile (Backup or Mirror profile) in 'Restore' mode. You may be prompted if you are sure you want to run the profile in Restore mode. If so, click Yes. The Restore Wizard will then appear.
At this point you can optionally click the "Choose sub-directories and files" button to choose which specific files and folders you want to restore. You can always skip unwanted files later in the restore process when the Differences window is displayed.
To Restore your files, click the Restore Now button.
Step 2: When the Differences Window appears, for all the files that have versions, it will show a small button next to the filename: 
When you click on the versions button, a new window appears displaying the list of version files available for that file with their Versioned Date, Modified Date and Created Date.
Step 3: Perform a Restore or Rollback
Step 3a: To Restore files using Version files:
1. Click on the versions button of a file from the Differences Window, a new window appears displaying the list of versioned files available for that file with their Versioned Date, Modified Date and Created Date.
2. From the list of version files, tick the version file you want to restore from and click on the ‘Select’ button. Note that the selected version file will be used for restore.
3. If the 'Action' in the Differences Window is shown as 'Restoring Version' then SyncBack will restore the selected file only on the Destination side. If you want to restore the selected file on both Source and Destination, then you may have to change the Action to "Copy to Source" from the Drop down list.
4. After selecting the version files for all the files in the Differences Window, click on the ‘Continue Run’ button to restore the files at your Source/Destination from the selected versioned files (based on the Action set in the Differences Window).
Step 3b: To Rollback files to a specific date using Version files:
1. Click on 'Rollback' menu on the top of the Differences Window. You have an option to rollback only your Destination files or both Source and Destination files.
When you select the rollback option and set the date/time to rollback, then for each file (that have versions) SyncBack tries to pick the version file closest to that rollback date/time and sets an ‘Action’ depending on the option selected (i.e. “Rollback all your Destination files” or “Rollback all your Source files”).
For “Rollback all your Destination files”:
If a file is selected for rollback then the Action is set as ’Restoring Version’ and only the Destination files are rolled back. Otherwise, the Action is set to ’Skip’ (that means the file is not selected for rollback because it was modified after the rollback date/time).
For “Rollback all your Source files”:
If a file is selected for rollback then the Action is set as ‘Copy to Source’ and both the Source and Destination files are rolled back. Otherwise, the Action is set to ’Skip’ (that means the file is not selected for rollback, because was modified after the rollback date/time).
2. When you select either the option “Rollback all your Source files” or “Rollback all your Destination files”, a rollback settings page appears, where you have to set the date/time you want to rollback your files.
Note that while configuring the date/time in the above settings page, you have to consider the modification date/time stamps of the versioned files. Then SyncBack will select the versioned files whose modification date/time stamps are closest to rollback date & time (but not after that date) and restore that versioned file on the Source/Destination (based on the Action set).
If SyncBack can’t find a version file with the modification date/time stamps before the rollback date/time, (that means if the file is not modified before the given rollback date) then that file is skipped and no action is performed.
3. The Differences Window displays the version file and the appropriate Action selected for each file before performing the rollback operation (you can also click on the versions button next to the file to verify the versioned file selected for that file).
4. Once you have reviewed the selected files for rollback, you can click on the “Continue Run” button to restore your Source/Destination files from the versioned files.
Please read the Help file > Using SyncBack > Runtime Help > Differences Window > Restoring Versions and Rollback for more details.