Storage allows you to see the storage devices attached to your FreedomBox and their disk space usage.
FreedomBox can automatically detect and mount removable media like USB flash drives. They are listed under the Removable Devices section along with an option to eject them.
If there is some free space left after the root partition, the option to expand the root partition is also available. This is typically not shown, since expanding the root partition happens automatically when the FreedomBox starts up for the first time.