The true value of coaching, however, is to build the capability of the existing team. Rather than making choices for the team, the coach provides guidance about the choices available, perhaps making recommendations, and encouraging them to consider the options and choose their actions. The coach teaches the team about techniques or tools that increase their available choices. The coach offers observations about the team’s activities, and helps the team make it’s own observations and reflect on them. The coach helps the team articulate the results it wants, and generate courses of action to achieve those results. The coach partners with the team on the coaching process, but allows the team to exercise its own judgement about the software development practice. The coach does not become a member of the team, but endeavors to wean the team off of the need to consult with the coach on a regular basis.

Source: http://scrumology.com/guest-post-what-is-an-agile-coach/