The original link is here.
Because Skype is a 32 bits software, you need to configure
pacman to be able to install 32 bits software through the
multilib repository. To do that, uncomment the following lines into
[multilib] Include = /etc/pacman.d/mirrorlist
Now, run some update of
pacman to be able to install Skype.
$ pacman -Syyu $ pacman -S skype