Complex sentence: Mariana de Jésus Torres, one of the young nuns, is said to have seen the Blessed Mother, who asked her if she would be willing to offer her life for the sins of the Twentieth century.
Split into simpler sentences: Mariana de Jésus Torres, one of the young nuns, saw the Blessed Mother herself. She asked her if she would be willing to offer her life for the sins of the Twentieth century.