or do you need to send the g-code to mach2 or something.

Visual Mill is a Cam program which generates the G code. You must then run the G code with a program such as Mach2 or Turbocnc for the drivers to be able to understand it.

VisualMill version 5 comes packaged with XPert DNC which can DNC (obviously) or batch send code to your machine. As well I have had good batch sending text (.txt) files to my control using Hyperterminal; which comes with MS Windows (or at least version 2000 and up)
There is also a free program called NCNet Lite http://www.cadem.com/ncnet/freednc.htm , which I never bothered to try as my VM upgrade came with Xpert DNC.

So I guess the true answer to your question is No; VisualMill does not do any "actual" cutting but is shipped with software designed to interact with most Machine controls.