Purgatory
What is Purgatory? Catholics consider purgatory as a place of punishment for what Catholics call venial sins. Here is a little bit about it from The Catholic Encyclopedia:
"Purgatory (Lat., purgare, to make clean, to purify) in accordance with Catholic teaching is a place or condition of temporal punishment for those who, departing this life in God's grace, are not entirely free from venial faults, or have not fully paid the satisfaction due to their transgressions. The faith of the Church concerning purgatory is clearly expressed in the Decree of Union drawn up by the Council of Florence (Mansi, t. XXXI, col. 1031), and in the decree of the Council of Trent which (Sess. XXV) defined: "Whereas the Catholic Church, instructed by the Holy Ghost, has from the Sacred Scriptures and the ancient tradition of the Fathers taught in Councils and very recently in this ecumenical synod (Sess. VI, cap. xxx; Sess. XXII, cap. ii, iii) that there is a purgatory, and that the souls therein detained are helped by the suffrages of the faithful, but principally by the acceptable Sacrifice of the Altar; the Holy Synod enjoins on the Bishops that they diligently endeavor to have the sound doctrine of the Fathers in Councils regarding purgatory everywhere taught and preached, held and believed by the faithful" (Denzinger, "Enchiridion", 983). Further than this the definitions of the Church do not go, but the tradition of the Fathers and the Schoolmen must be consulted to explain the teaching of the councils, and to make clear the belief and the practices of the faithful."
The Bible does not speak of any such place, or can the word "purgatory" be found anywhere in Scriptures. So where does it come from?
The Catholic Church created the idea of purgatory to cement power and extort money from the populace, for no other reason.
Purgatory DOES NOT EXIST!
To say that we must atone/suffer for our sins after death by cleansing in Purgatory is to deny scripture. Say that we have to continually suffer for our sins after death is contrary to everything the Bible has to say.
Further details on the Catholic tradition of Purgatory can be found here https://www.catholic.com/encyclopedia/purgatory.