Well , if you have started C++ right now , It would be hard to understand what int main () stands for, Most books explain the code as the place where the execution of the program begins.

And I tend to prefer it to be that way, until you get to "functions" . Once you are pretty much aware about functions , you will see that it all comes into place,
If you have already studied functions suggestion to you would be to consider revising through the book that you are reading and look again into Functions.

For a good reference you could use the basics of functions Here

[EDIT]
AND THEN if you have a doubt, you are always welcome to ask [/Edit]