WHAT IS A TEACHER ROLE?

A teacher's role is the way that he/she behave at different stages of a lesson to deal appropriately with the students. Those roles enable the teacher to set the tone of the class, build a warm environment, be a mentor for the students, become role models, etc. Teacher roles can vary according to the teaching approach that a teacher uses or the learning styles that the group of students has. 

Every teacher plays an important role in the students' lives. A teacher inspires and encourages them to acquire knowledge and make positives changes in the world.

Reference: 

Spratt, M., Pulverness, A., & Williams, M. (2011). The TKT Course Modules 1, 2 and 3. Cambridge ESOL.