Part of macOS
smbdFile Sharing
○ Leave it
Shares folders with other computers on your network.
What it is
Runs when File Sharing is on in Sharing settings.
If you stop it
Anyone connected loses their files. Turn it off in System Settings › General › Sharing instead.
The verdict
○ Leave it. Part of macOS, or something that starts again by itself. You never need to close these.
In Activity Monitor
smbdnfsd
From Procession’s guide, in the words the app shows.