Let's say each row sums to 15
If we had 3 rows, then the total sum would be 3*15 = 45
If we added all of the values in the 3x3 magic square, then we'd get 45 as well.
This is one example showing that
sum of all values = (number of rows)*(magic constant)
You can replace "rows" with columns to get the same idea, because each column also adds to the same magic constant. The diagonals are an exception since we only have two of them.
