How does Matrix Multiplication Work Using for-loop?

​​import java.util.Scanner;

public class MatrixMultiplicationExample{
  public static void main(String args[]){

    int row1, col1, row2, col2;
    Scanner s = new Scanner(System.in);
    System.out.print("Enter number of rows in first matrix:");
    row1 = s.nextInt();
    System.out.print("Enter number of columns in first matrix:");
    col1 = s.nextInt();
    System.out.print("Enter number of rows in second matrix:");
    row2 = s.nextInt();
    System.out.print("Enter number of columns in second matrix:");
    col2 = s.nextInt();

    if (col1 != row2) {
        System.out.println("Matrix multiplication is not possible");
    }
    else {
        int a[][] = new int[row1][col1];
        int b[][] = new int[row2][col2];
        int c[][] = new int[row1][col2];

        System.out.println("Enter values for matrix A : \n");
        for (int i = 0; i < row1; i++) {
            for (int j = 0; j < col1; j++)
                a[i][j] = s.nextInt();
        }
        System.out.println("Enter values for matrix B : \n");
        for (int i = 0; i < row2; i++) {
            for (int j = 0; j < col2; j++)
                b[i][j] = s.nextInt();
        }

        System.out.println("Matrix multiplication is : \n");
        for(int i = 0; i < row1; i++) {
            for(int j = 0; j < col2; j++){
              c[i][j]=0;
              for(int k = 0; k < col1; k++){
                c[i][j] += a[i][k] * b[k][j];
              }
              System.out.print(c[i][j] + " ");
            }
            System.out.println();
        }
    }
  }
}