Part of macOS
pboardClipboard
○ Leave it
Holds what you copy and paste.
What it is
Runs the clipboard.
If you stop it
Whatever you copied is lost. 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
pboard
From Procession’s guide, in the words the app shows.