The tribulation is also called the apocalypse or the end times. The tribulation is a time of suffering for the Church and the world, as described in the Apocalypse of John (the Book of Revelation). The tribulation is not the end of the world; it is a process of suffering and change that leads to the Return of Jesus Christ, followed by a long time of peace and holiness on earth.
The tribulation is divided into two parts. The first part is for our generation; this set of events includes the first six Seals in the Apocalypse of John, and the first six Trumpets of the seventh Seal. These trumpets and seals are a symbolic way to organize and order the events of the tribulation. The end of the first part of the tribulation (in early 2040) is followed by a brief time of peace and holiness on earth, just as the Blessed Virgin Mary described in the Secrets of La Salette:
21. “This peace among men will not be long; 25 years of abundant harvests will make them forget that the sins of men are the cause of all the pains which come upon the earth.”
After the time of peace ends, the sinfulness of the world gradually increases, generation after generation, century after century, until the time of the Antichrist in the early 25th century. At La Salette, the Blessed Virgin Mary said this about the second part of the tribulation:
33. “Behold the time; the abyss opens. Behold the king of kings of darkness. Behold the beast with his subjects, calling himself the savior of the world.
We can easily see from the 33 paragraphs of the secret given to Melanie at La Salette that the tribulation is much longer than 7 years or 3.5 years, as many claim. The 7 years is the length of the Antichrist’s reign, not the whole length of the tribulation. And the 3.5 years is the second half of the Antichrist’s reign, when he tries to destroy the Church by the assistance of the false prophetess.
The whole of the tribulation, then, is divided into two parts, with an inter-tribulation period between them. This division can be seen in the secrets of La Salette, which describes the end of the first part of the tribulation in paragraph 20, a brief time of peace in paragraph 21, and then the second part of the tribulation in later paragraphs.
See my book The Secrets of La Salette and the End Times for more on this topic.