Tempered glass is a hardened glass, specially designed to cover and protect the mobile phone screen from scratches and other damages. It does not affect the screen's functionality. In case the phone is dropped, the tempered glass protection does not guarantee that the screen will not break. However, it provides additional protection.
It is 3D, which means it has undergone special processing to have curved edges that cover the entire surface of the mobile phone screen. This way, it is not noticeable that the screen has protection, while at the same time the curved edges are also protected.