NLP stands for Natural Language Processing.
During the BERT algorithm update, Google introduced a machine learning component to better understand the content. They created a bunch of new metrics to analyze then to use NLP to understand what makes better content.
BERT analyzes the context, entities, and sentiment of the page. The ultimate goal is to make the search engine have a more accurate understanding of the content and its context.
Additionally, it recognizes the user's intent and the overall sentiment. By sentiment, we are talking about overall emotion for a word, sentence, and page as a whole.
We’ve added it to our platform via the Google NLP API which means you are able to see which words and phrases and sentiment Google feels are important,
Also, you’ll be able to compare your existing page to the top-ranking pages, so you can see how often you should be using these NLP entities. It’s factored into the Content Editor too.
We have a great article that goes into depth. The article walks you through all the specifics of NLP: https://surferseo.com/blog/nlp-on-page-seo-2020/