The phrase "to unlock the screen" means to remove the lock or security feature on a device's screen, allowing you to access its functions and content. Full definition
Make a note that if you have enabled pattern, password or other lock then you won't be able to access the notification panel from unlock screen. (phoneradar.com)
Now users can check the price chart of each cryptocurrency without unlocking a screen or launching the app. (cryptoninjas.net)
The software can tell the rest of the system whether your phone is inside or outside of that fence, and things like unlocking your screen can happen while you're inside the fence. (androidcentral.com)