Basically, it’s a calculator that can take letters, numbers, words, sentences, and so on as input.
And produce a mathematically “correct” sounding output, defined by language patterns in the training data.
This core concept is in most if not all “AI” models, not just LLMs, I think.
Pretty much.
But it only takes words as input. Numbers are just another type of word. Sentences are just a series of words with a “.” word on the end.
This is why when you get a LLM to do basic math it fails so often - it has no concept of a number or operations on those numbers.