i am new to C++ and Unreal engine.
so i think main () function is the main thing in the program. it will run all the program.
Since we’re doing this at the same time @Anji_Bmax, I’m gonna share my own first impression here as well 
I think the main() function defines the length of the game and how it will progress, depending on the “PlayGameAtDifficulty” function.
In other words, exactly what you said 
My own words on the tripleX code sections:
- #include brings up code from other programmers from a library
- main() tells the computer to run/read what we want it to do
- Expression statements tell it what to do
- Declaration statements tell it what the “building blocks” we defined are (variables, constants, etc.)