The Blessed Virgin Mary appeared to Lucy of the Dorothean Sisters, a visionary of Fatima, in 1925.  Below is from Fatima.org

On December 10, 1925, the Most Holy Virgin Herself appeared, and beside Her, borne by a luminous cloud, the Child Jesus. The Most Holy Virgin put Her hand on her shoulder and showed her, at the same time, a Heart surrounded by thorns which She held in the other hand. At that same moment, the Child said to her:

‘Have compassion on the Heart of your Most Holy Mother, covered with thorns with which ungrateful men pierce It at every moment, and there is no one to make an act of reparation to remove them.’

In other words, people are sinning against the Immaculate Heart of Mary and Jesus is asking for reparation for these sins by the faithful.  We are tasked to perform an act to pay the debt these unrepentant men owe. Continuing:

Then the Most Holy Virgin said:

‘Look, My daughter, at My Heart, surrounded with thorns with which ungrateful men pierce Me at every moment by their blasphemies and ingratitude. You at least try to console Me and announce in My name that I promise to assist at the moment of death, with all the graces necessary for salvation, all those who, on the first Saturday of five consecutive months shall receive the sacrament of Confession, receive Holy Communion, recite five decades of the Rosary, and keep Me company for fifteen minutes while meditating on the fifteen mysteries of the Rosary, with the intention of making reparation to My Immaculate Heart.’

So in order to make this reparation, 5 things are required on 5 first Saturdays.

  1. Receive the Sacrament of Confession
  2. Receive Holy Communion
  3. Recite 5 decades of the Rosary
  4. Keep Mary company while meditating on the 15 Mysteries of the Rosary
  5. Have the intention of making reparation to her Immaculate Heart.

The reward for performing this Act of Reparation is Assistance from Mary at the moment of death with all the graces necessary for salvation.

The thorns placed in her heart are summed up in what is known as the Five Sins against the Immaculate Heart of Mary.

  1. Blasphemies against the Immaculate Conception
  2. Blasphemies against her Perpetual Virginity
  3. Blasphemies against her Divine Maternity and at the same time the refusal to recognize her as the Mother of all mankind
  4. Blasphemies of those who seek openly to foster in the hearts of children indifference or contempt and even hatred for this Immaculate Mother.
  5. The offenses of those who directly outrage Her in her holy images.

It is important that we also teach our children to adore the image of our Immaculate, forever Virgin Mother of God and of all mankind!