By default on many modern HP laptops, the are primary. That means pressing F1 alone might mute the sound, while pressing Fn + F1 triggers the traditional F1 help function.
If your laptop is in "Action Keys Mode," pressing an F-key directly triggers the icon printed on it (e.g., muting audio or dimming the screen). fn key hp laptop
On standard HP laptops, you will find the key situated: By default on many modern HP laptops, the are primary
HP Notebook PCs - How to lock or unlock the fn (function) key fn key hp laptop