answer:
so there isnt such thing as a hertergon but if your looking for how much sides does a heptagon have
the answer is 7 !
ill add a photo here for you to see just in case i got the shape you were looking for wrong
but there isnt really any way to see how much sides a shape does have, the easiest way is to count the sides!
hope this help you and your problem! if you need anything else or if i didn't explain it well enough then please ask! hope you have a good rest of your day :)