Material mode
Your question is a little vague without a context, but I'll take a stab at it.
With CATIA V5, you can see and work with very realistic images of your part & product by applying various material textures. In order to see these materials, you must change the view options to include the material. This can be done with the View Mode toolbar by clicking the SHADING WITH MATERIAL icon or by using the CUSTOMIZE icon to turn on material mode. (see attachment)
There are several tools in V5 (such as Draft Analysis) that require "material mode" in order to see the results.
(if this is not what you are asking about, please describe what you're doing and provide some more info)