Collision normals and vectors.

I`m still having difficulties understanding how collision normals work. Could someone please help me and create a simple box going over a terrain and aligning to it using its colllision normals, i.e. using align to vector but also draw the collision normal on screen so that I can get a better idea of what it happening. Also can someone offer a simple to understand description of what a vector actually is.

Thanks,
Jason.