Okay kiddo, so F.X. Reid is a person's name. He is someone who has done some really cool things in the world.
But let's break it down even more. Have you ever heard of a scientist? Scientists learn about the world and how things work. They do experiments to figure things out.
F.X. Reid was a scientist who studied how chemicals work in our bodies. You know how your body has different parts like your heart, your lungs, and your brain? Well, F.X. Reid looked at the chemicals that help those parts work right.
He found out that some chemicals can tell your body to do certain things while other chemicals can tell your body to stop doing things. He also found out that if the chemicals aren't working right, then your body can get sick.
So, F.X. Reid was really smart and we can learn a lot from him!