I’m new here [the Church] so bare with me … what are indulgences? and why do these work off our cleansing in Purgatory? Also where is the scriptural evidence of this found (not purgatory but the works and indulgences for purgatory)?
What are indulgences?
The time or pain in purgatory may be lessoned thru our prayers, charity, alms giving, we do in our daily life.
The time or pain in purgatory may be even more lessoned thru certain prayers designated indulgenced by the church.
The reason being that if the church can forgive sins, then it can forgive suffering which is lessor than sin itself. And the reason being that there is a treasury of merits of Christ and the saints which the church has the power to dispense, just as she has the power to dispense the sacraments.
So the church has attached a greater merit to some prayers in order to encourage the faithful to say those prayers and bring them closer to Christ.
Every sin, from tiny to huge, we are accountable for and will be accountable for. That means we will pay for it, in this life, or in the next. Everything is written in the book of life.
The church is being very helpful to us in these indulgences to help wipe away the debt, some or all. That is what indulgences do.
Even sins that have been forgiven, there is a residue of payment still due. Sometimes one may have a notion that once a sin is forgiven, that that is the end of it. Not so. There is something remaining, not eternal payment, put some payment. How much we do not know until our judgment at death. But if we pray the indulgenced prayers, especially the full pardon ones, then we will be far more at ease to meet our judgment.
Here is a website of full pardon indulgences.
ourladyswarriors.org/indulge/plenary.htm
There is also a Handbook of Indulgences if you want to know more.