Under Display , do Surfaces . You get a box which lets you select the surface to view and it allows you to control some of the characteristics of the displayed surface. Try the different styles. Click on a surface definition to highlight it. Do one at a time.
Densities are electron density surfaces.
The 0.08 value provides a look approximating the bonds in a typical plastic or drawn molecular model. Negative elpot indicate areas which are prone to electrophilic attack. The -10.00 indicates the surface is a negative elpot. Property maps can be added to the electron density surfaces and use color to represent the value of the property. Red is negative and blue is positive.