newbie (to this site and to maya) here as well.

this is what I know (anyone feel free to correct me where necessary):

Maya Embeded Language (MEL) is a scripting language created by Maya that does everything you see visually when you open Maya. For example creating primitives, translating, rotating can all be done through scripts. The language is very much like
a mix between javascript, C/C++, and Perl.

Most things, if not all, can and I believe are actually done through scripts, in the background. So clicking an icon or selecting something from the menu actually just kicks off a script or scriptable command(s).

Look in your install directory in my case
D:\installed\Alias\Maya7.0\scripts - check out a file called
FileMenu.mel - that is what sets the file menu you see in Maya. Warning - don't change the file though.

Once you know how to script in it - I don't yet but learning - you can create menu items with windows in Maya as well as of course actually executing Maya commands for your scenes.

Other applications similar to Maya (3D Studio Max, Lightwave, etc.) have their own scripted language.