Furthermore, a plenary indulgence applied to the poor souls in purgatory is granted to the faithful who on every day from the 1st to 8th of November visit a cemetery and pray for the faithful departed.
Scroll below for a concise clip explaining indulgences.
Briefly, an indulgence is a remission of the temporal penalty for sin whose guilt has already been forgiven. Indulgences have a foundation in Sacred Scripture. In Second Maccabees the soldier Judah takes up a collection: “He also took up a collection, man by man, to the amount of two thousand drachmas of silver, and sent it to Jerusalem to provide for a sin offering…he made atonement for the dead, that they might be delivered from their sin” (2 Macc 12:43, 45).
The conditions for a plenary indulgence are as follows (excerpt from Vatican document The Gift of the Indulgence):
3. To gain indulgences, whether plenary or partial, it is necessary that the faithful be in the state of grace at least at the time the indulgenced work is completed.
4. A plenary indulgence can be gained only once a day. In order to obtain it, the faithful must, in addition to being in the state of grace:
— have the interior disposition of complete detachment from sin, even venial sin;
— have sacramentally confessed their sins;
— receive the Holy Eucharist (it is certainly better to receive it while participating in Holy Mass, but for the indulgence only Holy Communion is required);
— pray for the intentions of the Supreme Pontiff.
5. It is appropriate, but not necessary, that the sacramental Confession and especially Holy Communion and the prayer for the Pope's intentions take place on the same day that the indulgenced work is performed; but it is sufficient that these sacred rites and prayers be carried out within several days (about 20) before or after the indulgenced act. Prayer for the Pope's intentions is left to the choice of the faithful, but an "Our Father" and a "Hail Mary" are suggested. One sacramental Confession suffices for several plenary indulgences, but a separate Holy Communion and a separate prayer for the Holy Father's intentions are required for each plenary indulgence.