A polygon is a shape that has sides. A triangle is a polygon, squares are polygons. A circle is not polygon though. To draw a polygon on hopscotch, you'll need a reapeat block, how many sides does the shape you want to draw have, that's how many times you will repeat. So if it's a square, repeat 4 times, if it's a octogan, repeat 8 times. I'm drawing a dodecagon, (a 12 sided shape) so I will repeat, 12 times.
Now you'll need a leave a trail block, choose a color and a width. Moving forward is also your choice, keep in mind if your shape has lots of sides, you move forward shouldn't be as long. Now you need a turn block, get a division block. In the first space put 360, in the second put how many sides your shape has.