Why do I have 3 Macintosh HD - Data disk and how many do I need, also can I delete them.
MacBook Pro with Touch Bar
You should only have one; duplicates are usually the result of a reinstall of the OS. You can check them and if they do not contain any data, they can be deleted.
There is no need to erase and reinstall. Read through the thread here and follow the suggestions by Barney:
https://discussions.apple.com/thread/252051761
And to be clear: You should have a Macintosh HD volume and one Macintosh HD - data volume. The first one contains the OS and all system files and the Data volume contains your User folder and all other files/data.
Macintosh HD - Data
