Welcome to Android Central! I'm not sure what that's referring to. Show us a screenshot of the native system settings menu for Settings>Storage.
It's also possible that you might have a clone or knockoff S7--go to Settings>About Phone and tell us the exact model number. You can also run an app like CPU-Z and see what processor the phone has. If it's anything besides a Qualcomm Snapdragon or Samsung Exynos, then it's a knockoff.