1.
If something stands up to bad conditions, it is not damaged or harmed by them.
Is this building going to stand up to the strongest gales?
PHRASAL VERB : V P P n / -ing
2.
If you stand up to someone, especially someone more powerful than you are, you defend yourself against their attacks or demands.
He hit me, so I hit him back–the first time in my life I’d stood up to him...
PHRASAL VERB : V P P n