If we were to ask each of your references what type of person you are what do you think they'd say? How does that support your candidacy for a role as a sales manager?
To be successful in a sales manager job, it's not enough for you to be able to do the work. You have to be able to fit in as well. The interviewer here is looking to get to know you better and if there are any glaring fit issues standing in the way of your being successful in the job. Since you're being asked about what you think your references would say about you, this would be a good opportunity to bring them out. Have copies of any letters of recommendation as well as your reference contact information handy for the interviewer to refer to as you talk. That way you can illustrate and discuss at the same time. Give examples of how you came to know each reference and why they're important to your credibility as a sales manager. Be yourself and focus on presenting yourself as a positive addition to their workforce.