Imagine you have a big box filled with lots of toy balls of different colors like red, blue, green, etc. Now, let's say you want to group these balls based on their colors. You can put all the red balls in one box, blue balls in another, and so on.
But what if you had a magic box where you could put all the balls in just one box and still keep track of their colors? This magic box is like a field with one element.
In math, a field usually means a collection of numbers that can be added, subtracted, multiplied, and divided. But with the field of one element, you only have one number. Think of it as if all the toy balls in the box magically merged into one ball.
This one number behaves differently than other numbers. For example, if you add, subtract, or multiply this number with any other number, it will still be the same number. For instance, if 1 is the one element, then 1+2=1, 1-3=1, 1*4=1, and so on.
The field with one element is not usually used in regular math, but it is helpful in algebraic geometry, which is a kind of math that uses the properties of shapes and spaces to solve problems.
So, to sum it up, a field with one element is like a magic box with only one ball that represents all the balls in other boxes of the same color. This one ball behaves differently from regular numbers and is used in algebraic geometry.