The article by Gustavo Llermaly outlines a method for parsing body text into Elastic App Search, particularly when dealing with websites that have custom structures. Elastic App Search typically extracts text based on HTML tags into predefined fields, but this can be limiting when specific fields need to be captured, such as product details. To address this, Llermaly suggests creating a proxy server that interacts with the website's crawler requests, allowing custom meta tags to be injected into the response. This process involves setting up a NodeJS server to host a product page and a proxy server that modifies the page to include meta tags, enabling App Search to recognize these custom fields. The approach enables developers to manage and parse custom website data effectively without altering the original site structure.