Cement rendering is the application of a premixed layer of sand and cement to brick, cement, stone or mud brick. It is often textured, colored or painted after application. It is generally used on exterior walls but can be used to feature an interior wall.
Depending on the 'look' required, rendering can be fine or coarse, textured or smooth, natural or colored  pigmented or painted.
The cement rendering of brick, concrete and mud houses has been used for centuries to improve the appearance (and sometimes weather resistance) of exterior walls. It can be seen in different forms all over southern Europe. Different countries have their own style and traditional colours.