My homie Alfredo recently demoed how LLMs actually work to a couple of friends. He made it easy to understand.
He now published it as a blog post.

This post explores LLMs, the models behind services like ChatGPT, Claude, and Gemini. The goal is to give you an in depth but approachable understanding of LLMs, how they work, and how they are trained. We will ignore some details, and provide simplified explanations where appropriate.