The Internal Language of the Mind

I'm sure this has been thought of before and it is not so simple to put into words.

I was thinking, musing if you like:

Perhaps we really translate language somehow into a kind of internal language in our minds. A language of a symbols which are a complex of related memories and meanings.

Suppose someone gave a speech to three people.

One of those people didn't understand the language and so remembered little of the speech at all.
One of them partly understood and remembered some of it and the last understood it completely and remembered it well.

Later the last was able to repeat the speech but did not repeat the speech as spoken but a slightly different version with a similar meaning.

What is the difference? When you hear a speech you translate it into some internal meaning, some internal language of things meaningful to you in your mind. This is what you really remember, rather than the words themselves.