Coming from the Virgin Mary, this "Publish my glory" is surprising. We could object that all glory belongs to God first! If we are to be apostles, we should be apostles of the glory of God!
However, in Pellevoisin (1876 Marian apparition in France) Mary said to the visionary Estelle: "Publish my glory!" By this she meant: “Be a witness of the Love that is my whole life and that illuminates me from inside." Estelle received this mission not only to welcome in her heart the divine love that Mary revealed to her, but also to be a witness of it in today’s world.
Estelle was a sinner, like all of us, and she was not yet fully aware of the wound and offense she was doing to God. At the second apparition, she suddenly became aware of it. She then was so remorseful that she almost felt hopeless, thinking that her fault was so serious that she couldn’t be forgiven. It is then moment that the Virgin Mary said to her: "I am all merciful” and explained to her that God wants to forgive our sins to the end and that he is not afraid of our misery, nor of Estelle's sin. On the contrary, He wanted to use this sin to help Estelle to regain her trust in Him.
Mary came to visit Estelle to teach her how to grow in faith, hope and charity. As an educator, she taught Estelle to love. This is what it means to be at Mary's school. During the 15 apparitions, the Virgin Mary's gave many insights to Estelle, which the young woman used as practical advice to help her have a greater faith in God and in his merciful action. Mary taught Estelle to not put any limits to her trust. This is Mary's great pedagogy at Pellevoisin: she teaches us not to let go of her hand and to trust her in all situations.
In the apparition the Virgin Mary wore over her chest a special scapular of the Sacred Heart, expressing what is her most cherished treasure. The Heart of Jesus clothes the Heart of Mary! To wear the scapular is to tell the Lord that we desire to be clothed with his Love, like Mary.
Translated and adapted from:
https://www.pellevoisin.net/le-sanctuaire/message-pour-aujourdhui/