Purgatorio is a place that some people believe in. It's like a waiting room where people go after they pass away, but before they go to heaven. Think of it like when you're waiting in line to go on a ride at the amusement park - you're not on the ride yet, but you're not outside the park either.
People go to purgatorio when they're not quite ready to go to heaven yet. Maybe they didn't do anything too bad in their life, but they still have some things they need to work on before they can go to heaven. Purgatorio is a place where they can do that.
It's like a big, imaginary mountain with different levels. People start at the bottom and have to work their way up through different levels by doing things like praying, doing good deeds, and asking for forgiveness. Each level is a little bit harder than the last, but once they reach the top, they're ready to go to heaven.
But don't worry too much about purgatorio - it's just something some people believe in, and others don't. And even if it is real, it's still a place where people go to get ready for heaven, so it's not a scary or terrible thing.