What does this line mean?

[Hung Nguyen Gia <gh_origin%zohomail.com@localhost>]

For example:

# $NetBSD: bsd.prefs.mk,v 1.408 2020/06/07 05:59:30 rillig Exp $

How to get this line? Does it auto-generated or people add it manually?

If I edited the file, does I need to update it, too? How to update it?

Overwrite it with my information or append it or just another line like it but with my information?

And what does the 'v' mean? Does it mean 'version'? How could I know which version it is? Or I just put an arbitrary value?

Thanks.

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