Ok kiddo, I'll do my best to explain.
You know how when you eat food, your tummy breaks it down with help from tiny living things called bacteria? Those bacteria help you digest the food and make you feel better.
But sometimes, bad bacteria can take over and make you feel sick. That's where a fecal microbiota transplant comes in.
A fecal microbiota transplant (FMT for short) is when doctors take poop from a healthy person and put it into the tummy of a sick person.
Why would they do that?? Well, that healthy poop has a lot of good bacteria in it, and those good bacteria can help fight off the bad bacteria that are making the sick person feel bad.
It might sound gross to put poop in your tummy, but doctors make sure the healthy poop is super clean and safe before they use it.
FMTs have been shown to help people with a type of bad bacteria called Clostridium difficile (say: clo-STRID-ee-um dif-fuh-SEEL). This bad bacteria can make you feel really sick and is hard to get rid of. But when healthy poop bacteria is put into your tummy, it can help get rid of the bad bacteria and make you feel better.
So while it might seem like a yucky idea, a FMT can actually be a really helpful treatment for sick people.