confusion with fseek() in C

I am new to the C programming language. I am learning file I/O, and am confused with the fseek function. Here is my code

#include <stdio.h>
#include <stdlib.h>

struct threeNumbers 
{
    int n1, n2, n3;
}

int main ()
{
    int n;
    struct threeNumbers number;
    FILE *filePointer;

    if ((filePointer = fopen("\\some_folder\program.bin", "rb")) == NULL)
    {
        printf("error! opening file");
        /* if pointer is null, the program will exit */
        exit(1);
    }

    /* moves the cursor at the end of the file*/
    fseek(filePointer, -sizeof(struct threeNumbers), SEEK_END);

    for(n = 1; n < 5; ++n) 
    {
        fread(&number, sizeof(struct threeNumbers), 1, filePointer);
        printf ("n1: %d \t n2: %d \t n3: %d",number.n1, number.n2, number.n3);
        fseek(filePointer, sizeof(struct threeNumbers) * -2, SEEK_CUR);
    }

    fclose(filePointer);
    return 0;
}

I know that this program will start reading the records from the file program.bin in the reverse order (last to first) and prints it.
my confusion is I know that fseek(filePointer,-sizeof(struct threeNumbers),SEEK_END); will move the cursor at the end of the binary file. What does fseek(filePointer,-2*sizeof(struct threeNumbers),SEEK_CUR); do? I think it moves to the current location, but what is the point of the cursor cumming to the current location in this program? Also why is it -2 instead of being just -sizeof(struct threeNumbers)?

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