"To stand" usually means to maintain an upright position on ones feet. It can also mean to endure/tolerate/ support etc.
1) "It was a stand-out performance" means it was an exceptionally good performance - that is, it "stood out" from other performances because it was so good.
2) "He doesn't stand a chance" is an idiom, which means "he has no hope or prospect of success"
3) " ... What does he stand for?" means "What does he support?". Example: Think of "stand" = strong supportive position.
4)"... he stood me up ..." is an idiom, which means he left [her] waiting on [her] own, and didn't turn up.