Mary is Dead--- For the living know that they shall die: but the dead know not any thing.... Ecclesiastes 9:5
"Whenever a priest is consecrated a bishop and later named a cardinal, he adopts an official coat of arms. Typically this coat of arms is carried over if he is elected pope, though he could choose to modify it.
Update. Since this article was first published, the Vatican Secretary of State has posted a first image of the coat of arms.
It is expected that Pope Leo XIV will adopt a similar coat of arms to what he possessed when he was a cardinal.
One of the main features of his coat of arms is the emblem of the Augustinian Order, the religious order that he is a member of.
On his coat of arms is a book, upon which is a heart pierced with an arrow.
The Midwest Augustinians provides a description of the symbolism of the heart:
"The flaming heart is the human heart. It symbolizes Augustine's love of God and his fellow brothers and sisters. The Augustinian heart is passionately alive, with the desire to know God and experience divine love in our lives."
The other main image is the white fleur de lis (flour of the lily) on a blue background, a Marian image (though it can also refer to the Trinity).
The Pope's devotion to the Virgin Mary was evident from his first appearance, when he referred to the Madonna of Pompeii and asked the crowd to recite an Ave Maria with him."
Aleteia