It's the "solution" part that is important, i.e., agreeing on the border that satisfies both, solving other claims towards each other, removing the presence of each state from the other state's territory, etc.
The phrase was dreamt up by Western Israeli allies to promote an oppressive pipe-dream border arrangement that was not even remotely acceptable by any reasonable standards. Only propagandized westerners even speak of it.
This is done so the Western media can frame Palestinians as uncooperative.