Derivation:
Al-Lat in
Arabic means "the
Goddess" in the same manner that
al-Lah (
Allah) means "the
God." So
Herbert is implying an ancient cult of
sun worship, and the sun as a
female deity. (Ancient Earth cultures seem to have no consensus on the question of the sun's gender,
AFAIK.)
In Islam, al-Lat figures in the life of the Prophet Muhammad because she was one of the goddesses in the pantheon of the Arab pagan religion. Muhammad was instrumental in replacing this cult with monotheism.