Okay that os a great question. And I am a proud Gala myself. So, it is somali language, it means non Muslim. Somalis label their enemies as "galas" in times of war and jihad. Have used to wipe Oromos from around the borders and to loot our resources. After the Oromo revolution degmo, a man called Aba Bahere from around current day arbaminch modified the word "gala" to non chrisians, barbarians or pagans and introduced it to amharas and tigray monarchy. Generally, Gala means this who have no religion or their religion is unknown. A lot of Christian amharas mistake for Muslims. Nope.