Malachias was an irish archbishop.
In a vision, all future popes appeared to him. According to that, there will be 267 popes (John Paul II was the 265).
The prophecy says that the 265th Pope will remain exceptionally long in office (and he did).
Malachias predicts that the 266th Pope (Ratzinger) will only have a short tenure of office.
The prophecy says furthermore, that the last Pope will be called Peter and with him, the world’s going to end.