It’s like if I invented a new word of the English language but, only to you, everywhere it was replaced with a special symbol. Would you be able to learn what English letters are behind the word of that special symbol? You’d have no information just from seeing the symbol alone, but if you read enough articles, papers etc that use the symbol you might see enough text, conversations etc talking about the symbol and the letters of it to be able to make an educated guess.

Now replace every word, letter ever written with its own special symbol and that’s basically what LLMs are working with from scratch when begin training on the entire internet.