What does it mean to allow the lock screen to drop down the notification bar?

Allow screen lock drop-down notification bar is a setting option, which allows you to view or process notifications in the screen lock interface of your mobile phone or other devices. If this option is enabled, when the screen is locked, you can directly slide down from the top to expand the notification bar, and you can read and reply to notifications, such as text messages and social media messages. Screen locking refers to locking the screen of mobile phones or other smart devices by setting passwords, patterns or fingerprints to prevent unauthorized access and use.