When the light shines on the mirror, the mirror shines, but when the light shines on the wall of the room, why does the wall not shine?
Answer: Because the surface of the mirror is smooth, the light rays are reflected regularly in the mirror. In regular reflection the reflected ray moves in a specific direction. When viewed from that direction, the part of the mirror where the reflection occurs makes the area appear shiny.
The walls of the house are rough. Due to the diffuse reflection of the light rays on the wall, the reflected beam is scattered around. So the wall looks equally bright from any direction. So, when light shines on a mirror, the mirror shines, but when light shines on the wall, the wall does not shine.