These settings let you manage the data and configuration Sourcetab stores for you. To get here, in the settings, click on the "Data" button in the navigation.
This option lets you backup your data into a configuration file which is then downloaded.
This option lets you restore your data from a previous backup. You can choose to separately restore either widgets (with the option to replace or merge with your current widgets) or settings. Do not upload a corrupted or modified configuration file unless you know what you're doing. See here for the TypeScript interface of the configuration.
This option lets you reset your data (with the option of not resetting certain parts), changing it back to the default state. If you need to reset your data but can not access this option, delete then reinstall the extension, if you're using the web client, clear the local storage.