Complex sentence: Guyon's parents were very religious people, and they gave her an especially pious training, other impressions that remained with her where from reading the works of St. Francis de Sales, and her intercourse with certain nuns, her teachers.
Split into simpler sentences: Guyon's parents were very religious people, and they gave her an especially pious training. Other important impressions from her youth that remained with her came from reading the works of St. Francis de Sales, and from certain nuns, her teachers.