WP_DEBUG is an useful debugging tool available in WordPress to see PHP errors on your website and they are helpful for developers to troubleshoot issues with the website.
To turn on WP_DEBUG, add following code in wp-config.php
It is not advisable from security point of view to turn on WP_DEBUG on production websites as it will reveal sensitive information of your code and other information to website visitors.
So instead of displaying errors on the website, you can use WP_DEBUG_LOG to write error logs on a debug.log file and turn off displaying errors using WP_DEBUG_DISPLAY
To turn on WP_DEBUG_LOG and turn off WP_DEBUG_DISPLAY, add following code in wp-config .php
The debug.log file is located in /wp-content/ directory of your site.