The document explains how to import CSV or XML files into WordPress using the WP Ultimate CSV Importer, which allows both new data imports and updates to existing data, along with bulk image imports. It details the benefits of using CSV and XML files, including speed and compatibility with various text editors, and provides instructions on creating and preparing these files for import. Additionally, it outlines the installation and usage of the plugin along with its support for multiple languages and third-party add-ons.