This question is another way to ask about your strengths and weaknesses. By asking for specific performance evaluations, the hiring authority is more likely to get a direct answer and a better idea of the full picture.
If you do not have formal performance evaluations, you can also lean on a recent conversation with your direct manager. Your positive highlight can be big or small, but be sure to relate your positive points to the requirements of the Credit Union 1 job posting.
When you talk about your area for improvement, avoid mentioning something that would make you ineligible for the position. For instance, if you are interviewing for a banking position, simple math should not be your weakness. Also, be sure to discuss that you are actively working to improve this weakness.