On the question of where or what is hell?
It is answered, Hell exists inside the person body and mind.
The Early explanations from The Buddha
"N 15.1 Tinakaṭṭha Sutta
Grass and Sticks
How many mothers have we had in this saṁsara?
This is how I heard. At one time the Blessed One was living in the city of Sāvatthi, in Jeta’s park, at Anāthapiṇḍika’s monastery. The Blessed One addressed the monks, saying, “O monks!”
“Bhante!” those monks replied.
The Blessed One said, “Monks, this cycle of rebirth is endless. The beginning of this extremely long journey cannot be discovered. These beings, hindered by lack of knowledge of the true nature of life and bound by craving, roam and wander on in this endless journey.
Suppose, monks, a person would cut up whatever grass, sticks, branches, and twigs in the entire Indian Sub-Continent and collect them together into a single heap. Then, he cuts them off into four-inch pieces. Then, he would put each piece down, saying for each one ‘This is my mother, this is my mother’s mother.’
“The generation of that person’s mothers and grandmothers would not come to an end, yet, the grass, wood, branches, and twigs in all of India would be used up and finished.
What is the reason for that? It is because, monks, this cycle of rebirth is endless. The beginning of this extremely long journey cannot be discovered. These beings, hindered by lack of knowledge of the true nature of life and bound by craving, roam and wander on in this endless journey.
“For such a long time, monks, you have experienced various types of suffering, tragedies, and disasters. You have filled the cemetery with your dead bodies.
Therefore, monks, the time has come for you to understand the meaningless nature of all conditioned things. The time has come for you to become detached from them. And the time has come for you to be liberated from them.”
The idea is, that people or other animals cannot recognize hell in Samsara. The very nature of Samsara and Maya is like a prison house. People forget where they are because there are various pleasures in Samsara and their desire binds them to make the causes that produce the effect. It’s automatic cause and effect.
The Sutta above is a Theravadin Sutta so it contains partial and expedient teachings. The troubles and sufferings of usual Samsaric life causes beings to aspire to Nirvana and extinguishing their load of negative karma (sin). There is also good karmic causes but the Law is the same.
There is also Grace in Buddhism. It is called in Japanese, Tenju Kyoju=Lightening the karma and Hendoku Iyaku= changing poison into medicine.
