The whole thing is a girls audition. Her audition is a metaphor for life.
Shes dancing and working and trying her best, and each new step is another towards her future, another blotting out the things in her past she is ashamed of.
Meanwhile people look and judge how shes dancing and picking apart her faults because they are too blind to work on their own. (how she is living her life, and pursuing her passion, dance = symbolizing passion) They keep judging but she continues her dance and works through her heart, not through her bruised pride.

Finally it comes the time for the judges to review their scores and hold up their signs, but they are blank. Because in the end you never have anything else but what you grasp. It doesn't matter what they say anyway, its just you on your stage. There is no answer to the audition and the dancing never stops, life continues.

And the last line, if you know dancing, you know spotting is used while you dance, to keep your eyes focused so that you don't get dizzy or a headache. It means to keep your eyes set on your goal, your passion, and not get side tracked by frivolous things.