LLMs are large language models like Google Bard or OpenAI or ChatGPT, etc.
"It is a type of artificial intelligence (AI) algorithm that uses deep learning techniques and massively large data sets to understand, summarize, generate and predict new content."
When prompted "What's LLM?" - this was a portion of the answer given by Bard. There are several LLMs in the market, however their accuracy and content quality depends upon what amount of and which data sets they were trained upon.
Hope this helps.
Anni G