The interviewer wants to see that you are confident in your ability to meet this role's needs. They are also looking for evidence that you have researched the role and have a firm understanding of the responsibilities you will face, should you be the successful candidate. Discuss with the interviewer all of the things you have done to prepare you for this particular opportunity. Be sure to weave in details of the tasks and responsibilities that you understand to be required, and give specific examples showing how you have successfully taken on these responsibilities in the past.