understand how a structure variable is sent to a function

/*P2.28 Program to understand how a structure variable is sent to a function */
#include<stdio.h>
struct student {
        char name[20];
        int rollno;
        int marks;
           };
void display(struct student);
main( )
{
    struct student stu1 = {"John", 12 , 87 };
    struct student stu2 = {"Mary", 18, 90};
    display(stu1);
    display(stu2);
}
void display( struct student stu)
{
    printf("Name   - %s\t", stu.name);
    printf("Rollno - %d\t", stu.rollno);
    printf("Marks  - %d\n", stu.marks);
}