Control systems composed of several different parts just as program blocks
Your professor might like to have you think about the necessity of a linker. Since we don't know the stuff you already learned, it is hard to tell.

If you divide the source code of a whole application into parts, these parts need to call functions (subroutines) in other parts or access variables of other parts. Since you will translate each part separately, what problems might arise, if any at all?

Structuring an application with modules has several advantages; you will learn about them during your lessons.