In her “Little Way,” she taught that holiness (such as we would find in a Saint) can be attained while living ordinary, work-a-day lives. We need not live lives filled with great acts of heroic virtue.
This holiness extends to spiritual perfection, which is the complete aversion to all sin (as was taught about by the foundress of her Order, St. Teresa of Avila, and Teresa’s student, St. John of the Cross).
For her teaching about the Little Way, she was named Doctor of the Church (she is one of only four women Doctors).