It means "I bow to Shiva."

"Namah Shivaya" a beautiful phrase i finally made the effort to ask my yoga instructor the meaning to ...

 the supreme reality, the inner Self. It  is the name given to consciousness that dwells in all. Shiva is the name of your true identity- your self. 

After long stressful days, i force my lazy buttocks outa the house to rebalance, rejuvenate, revive my inner self...soul.....and energy..

 yoga and music is my key to sanity ...( http://www.youtube.com/watch?v=rq-1bxJc7F0 ) be inspired by "Namah Shivaya"