The sum of a regular hexagon's interior angles should be 720o and the sum of a regular hexagon's exterior angles should be 360o.
A hexagon cannot have a sum. There can be the sum of its interior angles, its exterior angles, its side lengths, its area (and that of some other area), or other characteristics, but not of a hexagon.
The total. sum of the interior angles of a hexagon are 720 degrees.
Sum of angles in a polygon is (n -2)180. Hexagon has six sides. So the sum of angles is (6- 2)180. (4)180 =720