It means we cannot be justified in knowing anything
Justification depends on a function that tells you whether something is justified. I can easily justify a belief with the fact that a teacher taught it to me.
In what sense do you think it can not be justified and why do you think that framework of justification has some sort of reality to it?
Something is epistemically justified if, as you said, it has some sort of reality to it not by coincidence but because the rule reliably shows what is real. I am trying to find a framework with some sort of reality to it, and that requires dealing with scepticism.
I've raised arguments for philosophical scepticism before, which have mostly been argued against in a Popper-esque manner of arguing that even if we don't know anything with certainty, we can have legitimate knowledge on probabilities.
The problem with this, however, is how you answer a sceptic about the notion of probability having a correlation with reality. Probability depends upon axioms of probability- how are said axioms to be justified? It can't be by definition, or it has no correlation to reality.