Looks like at some point you have tried erasing your Disk and reinstalling Catalina.
but instead of erasing the Disk you erased a Volume.
Installing Catalina effectively splits your SSD to two Volumes
Macintosh HD for the System and Macintosh HD - Data for your files.
When you did the erase you only erased one Volume and then installed Catalina back
onto that Volume which then was split to Macintosh HD and Macintosh HD - Data
leaving the original Macintosh HD - Data. so now you have three Volumes.
If you want to get rid of this situation you would have to erase your mac again
but this time erase the disk and then reinstall Catalina.
To erase your Disk open Disk Utility now click on View in the menubar
and select Show All Devices.
Now you will see in the left hand panel your Disk and its indented Volumes.
Highlight the Disk (probably called Apple SDD.......) and click on Erase
Give the Disk a name
Format: APFS
Scheme: GUID Partition Map
Click Erase
When done quit Disk Utility
Now reinstall Catalina, when installed you can restore your personal data
from the backup you made prior to erasing. Do not restore any system folders
or library folders as you will put your mac back to the same situation as before.