Complex sentence: In the stained glass window he is represented in the company of Françoise d'Amboise, duchess of Brittany and the founder of the first convent of the Carmelites in Vannes.
Split into simpler sentences: In the stained glass window he is represented in the company of Françoise d'Amboise. She was the duchess of Brittany and the founder of the first convent of the Carmelites in Vannes.