Why is the camera view pink in Unity 5?

I am a beginner. I created a 3D project with a cube object, and I am getting this pink display, in the camera view.

Can anybody throw some light on it?

pink is usually the color for an object that doesn’t have a material. your object is using the default material which is usually grey and uneditable except through code. from the scale and position of the cube and I assume the camera hasn’t been moved at all, that’s not even the cube visible but the skybox, which is then also broken.
this looks like a bug to me and you should try and reinstall unity completely