There is an angel that takes the impure souls to the cleansing process, aka hell. His name is Dooma, דומה. The English word ‘doom’ came from the name of that angel. (The Zohar is much older than English). This angel ‘punishes’ the body in the grave through a process of breaking down the matter until it becomes dust. Each body gets a different process.
Righteous people of the highest level don’t get this ‘treatment’. Their body stays in the same way as the day of their death until the Resurrection when their body will be restored to a younger state.
“זֹאת תִּהְיֶה תּוֹרַת הַמְּצֹרָע, בְּיוֹם טָהֳרָתוֹ: וְהוּבָא, אֶל-הַכֹּהֵן”
“This shall be the law of the leper in the day of his cleansing. Now he shall be brought to the priest”
After the soul gets cleansed in ‘hell’ it goes up to the lower level of the Garden of Eden. The soul feels the pain of being close to the righteous but cannot get inside and be with them yet. Gradually the soul gets purer and purer and becomes ready for the upper Garden of Eden. On that level the soul is welcomed and escorted by the Archangel Michael.
The Zohar tells us that all the sins can be cleansed except for evil speech on fellow man. The word Metzora מצורע has the meaning of ‘bring out bad’. This sin brings impurity to all of the body parts.
The power of words was given to us by God. It was initially used to create the world. When we use evil speech on others we release negativity for to the world. We can easily cure physical damage but it is very hard to control a spiritual damage.
Reading the Zohar is the best way to ‘cover’ evil speech sins. If you ask what is evil speech then consider evil every word that doesn’t have purpose or would hurt another person.