three
A stop sign has 8 sides, therefore it is and octagon.It also has a front and backside making 10 sides.
10 sides.
six if one consider it as a plane; one on this side, the other on that side, plus the top side, the side at bottom, the sides on the left and right. Something like a really thin and wide cuboid.
An n-sided polygon or n-gon, just like it sounds, has n sides. For example, a 13-sided polygon has 13 sides. A 24-gon has 24 sides.