I remember sharing with my parents my plans to become a coach some years ago. Their immediate response was, "what sport?" Having coached youth soccer and baseball over the years, I could understand their difficulty in comprehending just what a professional or executive coach actually does. My eleven year old daughter recently described what I do to one of her friends as "my dad talks to people and owns things." So you can see the difficulty that sometimes could exist in the market place not only regarding what coaching is, but more importantly how it adds value.
I think part of the confusion regarding coaching in organizations is actually caused by the similarities with coaching in sports. In both arenas the coach is tasked with teaching and guiding people to realize their full potential. The assumption is that we all have capabilities beyond where we are performing, and a coach, an outside perspective, can help us become more aware of the things that we believe and don't believe that are perhaps inhibiting our performance.
A coach asks questions to get you to think about or to think more broadly about your situation and challenges. A coach offers their perspective as a way to perhaps shift yours and challenges you to take action. Most importantly the coach provides you with the BIG eye, observing your thinking and behavior while teaching you to develop your own self observation skills.
A coach does not "fix" you, but provides a container of trust and openness where you can safely experiment with practices that help you step further into your greatness. I can think of no greater value add.