Your interviewer wants you to talk about your resume, and for you to walk them through your education and credentials by highlighting your experiences and how those informed your development and character. This will also help them determine if there are other skills or coursework or interests that you haven't found an application for professionally that might be of use in your position at the NSA.
On their website, they state they are looking for people with experience or education in history, government or political science, intelligence, foreign language, computer science/engineering/networking and security/programming, cybersecurity, data science and analysis, electrical engineering, information assurance, information technology or systems, data science and analysis, to name a few. "Your skills are key to our mission!"
