Remember that missing earpiece speaker grille on the front of this phone? That's thanks to Huawei's "Acoustic Display Technology" speaker, which works like a vibration speaker (a.k.a. structure-borne driver).
The driving part of this module consists of a coil with a magnet in the middle. It is coupled with the part that vibrates the screen, which is glued to the back of the display.
Don't confuse it with the conventional vibration motor for alerts, which is mounted on the metal frame next to it.