Surface Shader: Allows you to specify the look of the surface with a predefined surface shader.
Displacement Shader: Allows you to specify the bumpiness of the surface with a predefined displacement shader.
True Displacement: This toggel allows the selected displacement shader to actually alter the physical shape of the selected surface.
Diffuse: Allows you to specify the diffuse level and color you want the selected surface to have.
Specular: Allows you to specify the specularity level and color you want the selected surface to have.
Roughtness: Allows you to specify the size of specular highlights on the selected surface.
Luminosity: Allows you to specify how much luminosity and color you want the selected surface to have.
Opacity: Allows you to specify how much light will pass through the selected surface.
Shadows: Allow you to specify how this surface casts shadows. "None" casts no shadows, regardless of light source. "Opaque" casts a solid, completely black shadow, regardless of the surface opacity. "Transparent" casts a solid shadow affected by surface opacity, but not the surface shader. "Complex" casts a shadow affected by surface opacity and shader.
Apply: Applies the surface shader to the selected surface.
Remove: Removes this material from the selected polygons / patches.
Select: Selects all polygons / patches that have this material applied.