What is the file wp-config

One of the most important files in your WordPress installation is the wp-config.php file. This file is located in the root of your WordPress file directory and contains your website’s base configuration details, such as database connection information. It also has more advanced settings to configure WordPress Memory Limit(WP_MEMORY_LIMIT) and if Debug is active or not (WP_DEBUG).

Make sure to backup your file before edit it.