Pamac manager is another GUI frontend for Pacman with complete AUR support. That means that you can have both official packages from Arch repositories and un-official packages from AUR. The AUR repository is community driven repository that can be used to install packages which are not available in the official Arch Linux repositories.
Like tkPacman, you need to install Yaourt or Packer as mentioned in the above links to install Pamac manager from AUR.
After installing either Packer or Yaourt, run the following command to install Pamac as shown below.
packer -S pamac-aur
Aur Targets (1): pamac-aur Pacman Targets (2): itstool vala Proceed with installation? [Y/n] y