Executive coaching helps executives reach their potential by guiding them through a self-improvement process. The value of the coaching can only be defined by the executive and it should be through the achievement of tangible business value.
People come to coaching for several reasons: Firstly, they could just require some clear space in which to think and plan how to grow an organization or develop to the next level. The coach plays the role of an impartial guide free of judgement and politics.
Another reason is that the executive may believe that if they were to change/improve something within themselves, the greater organization and their development as a professional would benefit. They are looking for change, a different perspective, or have important goals to reach.