If one's urine is abnormally yellow, it usally means one need to drink more water. This is based on the idea of osmosis whereby if your body has too much water, it tends to leave your cells, thus diluting urine. If there is not enough water, your cells suck up water, thus making the urine stronger, deepening it's color.

If it is brown or red, it usally means that it contains blood. THIS IS NOT GOOD. you should see a doctor right away. This can be a sign of serious kidney problems.