Moisture analysis is a way of figuring out how wet or dry something is. Imagine you have a cookie and you want to know how much water or milk is in it. You might put it in an oven that's very hot for a little while. The heat will make any water or milk inside the cookie go away into the air. Then you can weigh the cookie again to see how much lighter it is. The difference in weight will tell you how much moisture was in the cookie.
Now imagine you want to do this for lots of cookies or other things, like soil, pet food, or medicine. You would use a special machine called a moisture analyzer. It's like an oven and a scale mixed together. You put the things you want to measure inside the machine and it heats them up just like the oven did. But at the same time, it weighs the things over and over again until there's no more water or milk to lose.
The moisture analyzer can then tell you exactly how much moisture was in the things you weighed. This is really helpful for making sure things are the way they should be. In the case of the cookies, it can help a baker make sure they're not too dry or too wet. For soil, it can help a farmer figure out when to water his plants. And for medicine, it can help make sure the pills have the right amount of moisture so they'll work the way they're supposed to.