Which is better? ;)
 

"This is a place where is easy to sale something"

OR

"This is a place where it is easy to sale something"

Thank you :)

neither dude, use 'sell' instead of 'sale'

So "This is a place where it is easy to sell something" for example

Debates around "is" are totally kicked me off so I can't think anymore :)
So, the word "is" is required in this construction, right?

This is a place where it's easy to sell something, yep

what do you have for sale?