The answer you received was intended to help but it expected a little work on your part.
Anyway, I'm not a raw beginner but I'm no expert either. So I'll only attempt to give you a short example.
the function printf() in the above example will print "Hello World!" to your screen. The stdio.h is a header file which allows you access to this pre-written function, without you having to write the code needed to print to screen. There are many other functions accessed using this header file and the same applies to the other header files you have listed.
My explanation may have some flaws in it so I'm sure there will be someone out there who'll correct me if this is the case.
Hope this is of some help.