My brother got a Ps4 but we don't know what the Ps key is
The button under the touchpad and between the two sticks with the Playstation logo on it. If it is an original controller.
The PS button is the one between the analog sticks with the Playstation logo. This has various functions and is used, among other things, to switch on the controller and thus also the Playstation. You can also use it to switch between the current application and the main menu and if you hold it down, you get to a kind of quick menu…
You will get all functions out over time…
As far as I know there are the functions:
PS button:
Turn on the PS4 ™ system (when the PS4 ™ system is off or in sleep mode).
Display the home screen (if the PS4 ™ system is switched on).
PS button (double press):
Switch between applications used.
PS button (long press):
Show quick menu. The currently available commands and settings are displayed.
Cool… Dat with the double press I did not know yet…