Imagine you have a big box with lots of different colored blocks. You want to organize these blocks so that all the blocks of the same color are in the same place. But, you don't know how many different colors of blocks there are or how many of each color there are.
A growing self-organizing map is like a person who helps you organize the blocks. They start by looking at one block at a time and figuring out what color it is. Then, they put that block in a place where other blocks of the same color have been put before. If they find a block that is a different color than all the other blocks they've seen before, they create a new space for it to go.
As they keep looking at more and more blocks, they start to see patterns and group blocks that are similar together. So, if they see two blocks that are a little bit different but still kind of the same, they put them near each other.
Eventually, they will have organized all the blocks into groups of different colors. And if they find a new color of block that they haven't seen before, they'll create a new group for it.
A growing self-organizing map is basically a way to group things together in a smart way, even when you don't know exactly what you're looking for at first. It's like having a friend who is really good at organizing things and can help you put everything in the right place.