I think it needs a little rephrasing as those with not much arch experience may be confused.
Pacman will install a backup of the file /etc/s6/s6.conf as s6.conf.pacnew. Do not forget to make the change on this file before rebooting.
I think the term backup is wrong, the newly installed .conf file is stored as .pacnew and the old is left as s6.conf
You should backup your old, make changes to .pacnew (timezone, hostname, etc) and save it as s6.conf
A very tedious task on Arch but check on the arch-wiki for help.
If you don't make the changes listed on Eric's bulletin you will not even make it to tty2 on the next boot!