Gehenna is the Hebrew. It's translated into the word "hell" in the Christian old testament.
Hell in Christianity is completely different than in Judaism. There is no such thing as some eternal burning hell, in Judaism. There is a place called Gehenna that we may go to in order to "burn off" any blemishes we have caused to our souls. This is not a permanent place, but is temporary lasting no more than 12 months.
While we are there, the pain we feel from the "burning off" is not a punishment, but comes from seeing and feeling every single bit of pain and suffering we ever caused anyone. It is like seeing a movie review of your life, only you FEEL everything you caused anyone.
The pain this causes us as we see the harm we did, and we see the many choices we could have made - and what errors led us to choose as we did instead, this pain is horrendous. We make complete, total tshuva (repentance, turning from ever doing those things again) and we leave there having gained a great deal in wisdom, understanding, and compassion.
At that point we may reincarnate in order to help others, or to meet any other situations that caused other types of blemishes we may have brought about in past lives that we need to work out in the new life. Some blemishes are best cleansed in Gehenna, some are best cleansed by reincarnating, it depends on the blemish and the level of understanding of the person themselves.
There is no such thing, there has never existed in Judaism, a God who would throw his creation into a burning hell of torture for all eternity. This is not the God of Israel.
This is traditional, Orthodox Judaism. Reincarnation has ALWAYS been a foundational belief. If you are interested in learning more, please Google "Judaism Reincarnation". There are many books written on the topic as well, such as Shaar haGilgulim, etc.
P.S. There is a limit to this however. If a person after 3 lifetimes is continuing to blemish and cause great harm to itself and others rather than repair, God will destroy that soul out of mercy rather than allow it to continue.
And P.S. There is no such thing as Original Sin, in Judaism. This was invented by Augustine of the Catholic Church, he was later made a Saint.
You can see how very, very different Judaism and Christianity are, and this is just the tip of the iceberg. There is literally nothing in their doctrines or foundational beliefs that is the same at all. Total opposites.