Ok, so imagine you have a big circle that has lots of different smaller circles inside of it. Now let's say each of those smaller circles represents a different person's soul.
Shaar Hagilgulim is like a door or an entrance way that connects all of these different circles together. It's like a secret passage that allows the souls to travel between different bodies throughout time and space.
So, if someone's soul was in one body and then that person passed away, their soul could then use Shaar Hagilgulim to enter into another body that was waiting for it to enter. It's like a never-ending cycle where the souls keep moving and changing, but they're all still connected through this special door.
People who believe in Shaar Hagilgulim think that this process helps souls grow and learn new things by experiencing life in different bodies. It's kind of like changing outfits every day and learning something new about yourself every time you put on a new outfit.
But remember, this is just one belief and not everyone believes in Shaar Hagilgulim or this idea of the soul traveling between bodies.