The term refers to pirated software — WordPress themes or plugins that have been cracked to remove license protections. Using nulled themes is:

The most common risk is the injection of malicious code. Nulled themes often contain backdoors—hidden scripts that allow the attacker to access your server remotely.

A "nulled" theme is a premium product that has been modified to bypass license verification. While it may look functional, the risks are substantial: News & WooCommerce WordPress Theme - Newspaper

: Access over 1,300 pre-made design templates that allow you to customize posts and pages from the front end without any coding.

: A custom, frontend drag-and-drop page builder designed specifically for news layouts, allowing users to customize every element without coding.