I didn't write the example unfortunately. Its a Unix-like terminology there. On a Linux system the base install is known as localhost.localdomain And I now see its an absolutely awful example - it bears no relationship to a Windows XAMPP installation.
This is a working vhosts example...
# duplicate the installed root/default
<VirtualHost *:80>
ServerAdmin
johnb@newnetenterprises.com DocumentRoot "/xampp/htdocs"
ServerName bravo.newnetenterprises.com
##ServerAlias bravo.newnetenterprises.com
ErrorLog "logs/bravo-error.log"
##CustomLog "logs/dummy-host.localhost-access.log" combined
</VirtualHost>
# start the vhosts entries:
<VirtualHost *:80>
ServerAdmin
johnb@newnetenterprises.com DocumentRoot "/xampp/sites/en.newnetenterprises"
ServerName en.newnetenterprises.com
##ServerAlias en.newnetenterprises.com
ErrorLog "logs/en_bravo-error.log"
##CustomLog "logs/dummy-host.localhost-access.log" combined
</VirtualHost>
<VirtualHost *:80>
ServerAdmin
johnb@newnetenterprises.com DocumentRoot "/xampp/sites/es.newnetenterprises"
ServerName es.newnetenterprises.com
##ServerAlias en.newnetenterprises.com
ErrorLog "logs/es_bravo-error.log"
##CustomLog "logs/dummy-host.localhost-access.log" combined
</VirtualHost>
....
I have 4 more in the setup. I just cut & pasted them after I had pattern (as you can tell from the ServerAlias) They are language variants of a series of WordPress CMS's
Note that ServerAlias and CustomLog are optional fields, you will FOR sure want separate error logs.
the DocumentRoots would be folders with pathnames in 'windows drive letter format' if they are outside the ServerRoot.
for instance:
DocumentRoot "/xampp/sites/en.newnetenterprises"
could be
DocumentRoot "e:/sites/en.newnetenterprises" instead
The reason I put my sites (the vhosts files) inside the ServerRoot was simple, I had plenty of disk space, AND by doing that I could run a single daily backup and get all my XAMMP sites and work in one pass. It really does not matter where you put them (don't put them in C:\users -- many many bad things can go wrong that way). However - BE SURE TO BACKUP!
If you want to use domain names for them - particularly if they mirror 'real-world' sites, you would add them to your hosts file. That way DNS will use them exactly as if they were in the real world - but never try to connect to your real servers. You would need to fix outbound calls etc. as well
I have my own DNS and servers, so I 'fix things there', but for those sites (if I only wanted to access them from the machine I was on) - the entries in the hosts file would be
127.0.0.1 bravo.newnetenterprises.com
127.0.0.1 en.newnetenterprises.com
127.0.0.1 es.newnetenterprises.com
...
You should also read that Apache page, as I think its quite clear really - after my last explanation here. I didn't realize what an awful example was given.
Good Luck