How do I avoid the Player to see behind a wall?

How do I avoid th Player to see behind a wall?

Here you can find my video game: drive.google.com/file/d/1VJorWsjLm9oiNrm9j-wQhaRgGFaHKbIO/view

Thanks for yours answers!

you can use shadow for the wall, and put the light on the player. The idea would be to put the shadow on top or as a mask to the enemy.

Ok, but I don't how yo put the light on the player