Feb 8 11:02:28 server nmbd: msg
That appears to be a syslog entry (like what you would find in /var/log/messages on a typical Linux system).
If so, there's the obvious "date", "time" and "hostname" of your server, which is named "server"; then the process name and process id of who logged the entry, the "nmbd that you asked about. Not really a code, but an identifier of what (who?) logged the message.
The process ID or PID (the number between the brackets ) is not mandatory and is at the discretion of whoever is logging the entry, so it can be missing in some entries. Do a 'man logger' to see a shell command interface to syslog; or 'man -s3 syslog' to see the c language interface to syslog if you are curious.
You should be able to do a 'man nmbd' to get the man page for nmbd, but here is an online one http://linuxcommand.org/man_pages/nmbd8.html
Google nmbd to get more info on that. It's part of Samba.