So, you know how when you need to go poo-poo, you go to the bathroom and sit on the toilet to let it out? Well, sometimes, some people have a problem with their colon (a long tube in their tummy where the poo-poo goes through) and they can't go poo-poo normally.
When that happens, the doctor might do something called a colotomy. This means they make a little hole in the tummy and connect the colon to it, so the poo-poo can come out through that hole instead.
It's kind of like making a new way for the poo-poo to leave the body, so that the person can still be okay even though their colon doesn't work like it should. And after a while, they might even be able to go back to normal poo-poo like you and me!