There is no such thing as a congruent hexagon. You need to have multiple hexagons for them to be congruent. They are congruent if they have the exact same angles (in the same order clockwise) and the exact same side lengths. read more
Second, congruent means the polygons are the same size and shape. Third, regular hexagon means that all of the angles and the same and the lengths of the sides are the same. For my explanation, let's work with squares. read more