This is becaue the interior angles of at least 3 hexagons that meet at a single vertex add up to 360 degrees.
Note: The number of sides in a polygon is equal to the number of vertices.
More precisely, no internal angle can be more than 180°.
The hexagon is an excellent shape because it perfectly fits with one another to cover any desired area.
A stop sign is an example of a regular polygon with eight equal sides.
For the regular hexagon, these triangles are.