apt-get install language-selector
gnome-language-selector ar

apt-get install language-pack-gnome-en
apt-get install gnome-user-guide-en
apt-get install language-pack-ar
apt-get install gnome-user-guide-ar
apt-get install language-pack-gnome-ar
apt-get install language-support-input-ar
apt-get install language-support-writing-ar
apt-get install language-support-fonts-ar
apt-get install language-pack-ar