The Barzakh is a life which has a barrier between this world that we live in and a life of a certain type with its own reality. It is nothing like this world. It is not the hereafter nor is it this world, it is somewhere in between.
Allah says in the Quran:
… between them there is a barrier the two seas do not mix. (55:20)
Allah used the word ‘Barzakh’, and the same word is used for that life after here, before the Day of Judgment. Allah says in the Quran:
… and behind them there is a barzakh world until the day you are resurrected. (23:100)
This points out to us that there is a life barrier that does not mix with this life. You can’t mix. You don’t know what’s happening to them, they don’t know what’s happening to you, and you cannot understand them.
As soon as you die, the soul begins to experience the barzakh world.
If you want to get a closer image to your minds in a very slight example, it’s not exactly like that, consider dreams. When you’re asleep, your body is in the room and everyone can see your body, witness your body, touch your body; but your soul is doing something different, seeing something different, hearing something different. It’s in a different place.
For a person who is awake, all I can tell you is I see a body that’s sleeping, but you’re in a whole different world. Some people don’t even know that they’re sleeping, they think it’s reality; and some people know that they’re sleeping when they’re dreaming.
The barzakh world is similar to when your soul goes out when you’re asleep. You don’t require oxygen (for your soul). Have you ever seen yourself in your dream underwater? The soul doesn’t need to survive on what your body survives; the body survives on food and oxygen, but the soul doesn’t.
So, if you can understand dreams, you can understand the barzakh. As for me, I don’t think anybody understands the phenomena of dreams and the way the soul comes out when you’re asleep, and similarly we cannot comprehend the barzakh world.
This barzakh world is a temporary station between here and the hereafter (the Day of Judgment). In this temporary barzakh world a person is able to find out if they are going to heaven or hell.