A literacy coach, sometimes called a reading coach, is a reading specialist who provides professional development on literacy issues for the teachers in her school building or school district. You would most likely need a master's degree in reading for this career in education. This professional development would include new techniques to try with students, information on current literacy research, help with struggling readers, lesson plans, and anything else the literacy coach, school administration, and classroom teachers feel would help develop a long-lasting and successful literacy program in the school or district.
The term "coach" is used because a literacy coach is training her team of teachers to become better reading and writing teachers. It is the coach's responsibility to provide professional development in areas where teachers are struggling, just like it is important for a football coach to provide his players drills in their weak areas.