if you are humbled, you realize that you are not as important, good, kind etc as you thought you were:
You can't help but be humbled when you enter this cathedral.
to easily defeat someone who is much stronger than you are:
The mighty U.S. army was humbled by a small South East Asian country.
to show that you are not too proud to ask for something, admit you are wrong etc:
I knew he had humbled himself to ask for my help.