How do I use an array variable inside an array of structures?

I'm trying to grasp the concept of arrays of structures and came up with a problem. Hopefully you can help me out.

Okay, so, the problem I'm facing is how to declare and use (i.e. accept & display values) of an array variable within an array of structures?

This sample code may visually help you to understand my problem:

#include<stdio.h>

struct node{

    int roll;
    char name[10];
    int grades[5]; // Accepts 5 grades for each student
};

int main()
{
    struct node student[3];

    /*Accept and display values for structure members here*/

    return 0;
}

I know there's a similar example here.

But I don't understand line 4 in the accepted answer's main() section, where memory is allocated using malloc() :

list[ip].inputs[inp]= (char*)malloc(25);

I'm getting confused between the 25 bytes allocated here and the 10 defined in char* inputs[10];

What exactly is happening here? And how do you solve the problem I mentioned above?