Complex sentence: The affranchi were light-skinned (mulattoes) free persons of color, the offspring of white French men and African women, the affranchi had legal and social advantages over the slave classes.
Split into simpler sentences: The affranchi were light-skinned (mulattoes) free persons of color, the offspring of white French men and African women. As such, the affranchi had legal and social advantages over the slave classes.