It implies that the person who used the phrase has superior knowledge, skill, or understanding compared to the other person.
Think of it like getting a lesson in humility - you learned something new (or rather, learned how much you *didn't* know).
Here are some examples of how it might be used:
* "You just got schooled on that history fact! It wasn't the Romans who invented concrete, it was the Greeks!"
* "I just schooled my opponent in a chess game. He didn't stand a chance!"
* "You think you know about video games? You just got schooled by a ten-year-old!"