Enabling pop-ups in Mozilla Firefox allows certain website features to function properly, but browsers often block them by default. To use features like forms or notifications, it's necessary to allow pop-ups. The process for enabling pop-ups varies slightly between Windows and macOS users, involving checking the "Block pop-up windows" box and then adding exceptions for specific websites. Alternatively, blocking pop-ups can be achieved by ticking the checkbox in the Permissions section of Firefox settings. It's recommended to enable pop-ups only for trusted websites requiring them, and using an ad blocker or installing add-ons like uBlock Origin may help block intrusive pop-ups.