3) At the left of Our Lady and a little above, we saw an Angel with a flaming sword in his left hand; flashing, it gave out flames that looked as though they would set the world on fire; but they died out in contact with the splendor that Our Lady radiated towards him from her right hand: pointing to the earth with his right hand, the Angel cried out in a loud voice: ‘Penance, Penance, Penance!'. And we saw in an immense light that is God: ‘something similar to how people appear in a mirror when they pass in front of it' a Bishop dressed in White ‘we had the impression that it was the Holy Father'.

In simple words, it's asking us to do penance for our sins and asking for peace on earth.