The various views available are quite self-explanatory. The 'Top', 'Left', 'Right', 'Front' and 'Back' views show you the views from each of those directions.
The 'Iso' view is an isometric view. In this view the angles between all the axes appear the same in the view window. This allows you to see the model in a more real 3 dimensional perspective. Note that you can use the 'Orbit', 'Pan' and other tools to move around your model in any direction starting from any of the basic views.
You can access the View Settings either by adding the toolbar using 'Views' -> 'Toolbars' -> 'Display Style', or you can access them through the 'View' -> 'Rendering' pullout.
'Wire frame' view displays just the points and lines in a model. This view is used when you want to create shapes that are highly interconnected, or want to check to ensure that lines are correctly connected to the right points in the right planes. Note you cannot use surface modification tools like the 'Push/Pull' tool while in this view, as it does not display surfaces.
'Hidden Line' view displays the view with all points, lines and surfaces without textures. This view gives you a simple look at your model without a lot of color and textures that might make certain features difficult to see and some mistakes hard to spot.
'Shaded' and 'Shaded with Textures' are similar. They display the model with textures, in the case of the 'Shaded' view, it converts the texture to a color and displays just the color on the surface.