What does the fortune teller mean by letting him come back at night to sprinkle salt?

Hello, my friend, when you are original, count your fingers, that is, the master told you to keep a low profile. Can't show off, it is easy to lead to jealousy and ruin!

This sentence comes from Xiang Yu. Chu overlord entered Xianyang, burned Epang Palace and went back to his hometown to show off. Finally committed suicide!