It means your body is dumping acid. If your urine is acidic all the time then you need to alkalize your body.
Calcium is one way. Baking Soda will work quickly but you don't want to do it all the time. Colloidal minerals and eating certain types of foods is better over the long run.
A better indicator is the saliva. Your blood has to be a certain PH or you will die. To maintain blood ph calcium and minerals are taken from the body and bones. If your blood is trying to alkalize your saliva will be more acidic.