Imagine you have a toy box filled with different kinds of toys. Some toys are big and take up a lot of space in the box, while others are small and take up less space. Now, let's say you want to measure how much space the toys take up in the box. The bigger toys take up more space than the smaller ones, so you can say that the big toys have a higher "spread" than the smaller ones.
In math, we use a similar idea to measure how much a function "spreads out" over a certain set of points. This is called the function's "analytic spread." Just like the big toys took up more space in the toy box, functions with a higher analytic spread take up more "space" over the set of points they're defined on.
To understand this better, let's use a graph as an example. Imagine you have a function that looks like a big wave, going up and down over a certain set of points on the graph. This function would have a high analytic spread, because it's taking up a lot of "space" over that set of points. On the other hand, imagine a function that looks like a straight line on that same graph. This function would have a low analytic spread, because it's not taking up as much "space" as the wave.
So, to summarize: analytic spread is a way of measuring how much a function "spreads out" over a certain set of points. Functions that take up more "space" over that set of points have a higher analytic spread, while functions that take up less "space" have a lower analytic spread.