How do the examples and illustrations work? New understanding?

A question I pondered today: How do examples and illustrations create new understanding?
In more detail, we can think of two types of examples: (a) those that bridge details and lack of knowledge that are not made clear in the body of the argument. (b) those that illustrate the argument itself. In what follows, I am referring to the second type.
And I'll give you – how could I not – an example: Let's say a child has difficulty understanding that one plus one equals two, and the moment this is illustrated to him with an apple and another apple equals two apples, he understands. What happened here? It's hard to say that he disagreed with the argument itself, because if so, the example wouldn't have helped, so what did happen here? Why do we suddenly understand through implementation?
[The truth is that perhaps it can be said that, and as you explain about rhetoric, that it manages to 'transport' a person from one point to another. However, that's not exactly what I'm talking about, but rather more frequent situations]
Another example: I studied with a guy who couldn't understand Migo's theory, but as soon as I told it to him as a story with an illustration – he understood. What was going on here?
I have some lines of explanation, but something here eludes me and I can't figure it out.