I understand it as this:
Buddha is referring to the absolute truth or a mind that has completely seen and experienced that truth, hence free from suffering, hence having attained Nibbana. When one comprehends the PS to a certain extent (by entering the noble path), one can see/experience that truth (to that same extent) and one “sees” the way to ultimate liberation/truth, or Nibbana.
Edit: The responses below didn’t show up until after I posted this. They are a bit more detailed!
