About Google One
From the developer's description on Google Play.
The Google One app lets you automatically back up your phone and manage your Google cloud storage. • Automatically back up the important things on your phone, like photos, contacts and messages using your 15 GB of storage that comes with every Google account. If you break, lose or upgrade your phone, you can restore everything to your new Android device. • Manage your existing Google account storage across Google Drive, Gmail and Google Photos.
Upgrade to a Google One membership to get even more: • Get as much storage as you need for your important memories, projects and digital files. Choose the plan that works best for you.