"What did you learn from your internship?"
If you worked as an intern, your resume will say it. Your resume should also include a list of what you learned during your internship. You can answer this question repeating what was on the resume, but using full sentence and with more enthusiasm.
"In my final summer vacation, I had the opportunity to work as an intern for a public accounting firm. It was only for 3 months, but I learned a lot about performing quarterly tax services for small and medium size companies. I also learned to deal with time pressure and learned how to prioritize work to be more efficient. It was a great experience that I know will help me when I start my career."