Public speaking can be intimidating! Assure the interviewer that you are capable of giving presentations. If you have given presentations, you can also mention the topic, what the setting was, and how many people you presented.
Example so it can be easier:
“In my last two roles, I have been responsible for regularly presenting to my team of 43 staff as well as to our entire warehouse team of over 200. I have taken a couple of Toastmasters sessions which helped a great deal. I am a confident public speaker.”