In c++

How do struct work and how do all of these relate to each other?

(you don't have to do the questions please just explain how the struct and its variables are related to each other)

struct nameType struct courseType struct studentType string first: string last; string name; int cal1Num; int credits: char grade; nameType name: double gpa; courseType course: studentType student; studentType classList[1001: courseType course; nameType namei