Part of macOS
diskarbitrationdDisks
○ Leave it
Mounts and looks after disks and disk images.
What it is
Handles connecting, checking and ejecting disks.
If you stop it
macOS starts it again straight away. Leave it.
The verdict
○ Leave it. Part of macOS, or something that starts again by itself. You never need to close these.
In Activity Monitor
diskarbitrationdapfsdstoragekitddiskimagesiodDiskUnmountWatcher
From Procession’s guide, in the words the app shows.