A square minute is like a little piece of land. Just like how your backyard is a piece of land, a square minute is a small area of land that is the same size as a square that measures one minute on each side.
Now, a minute may sound like something that we use to measure time, and that's true! But it can also be used to measure distance. In this case, when we talk about a square minute, we're talking about an area of land that is one minute across on each side.
We can use a map to understand this better. Imagine we have a map of a certain area, and we want to know how much land is in a square that measures one minute on each side on that map. We can draw a square on the map, with each side measuring one minute, and all the land that's inside that square is what we call a square minute.
It's like a tiny puzzle piece of land, and when we put all the square minutes together, we get the whole picture of how much land there is in that area - just like how you put puzzle pieces together to make a bigger picture.
In short, a square minute is a small area of land that is measured by a square with one minute on each side, and it helps us understand the size of the land in a certain area.