Translation is a broad profession and encompasses any number of text types - literature, articles, scientific studies, patents, subtitles for movies, and much more! The interviewer is looking for what texts will likely give you the most energy and excitement, and they might be exploring whether or not your interests align with the texts they often receive. When providing a response, be sure to choose a text type that you have some experience in - you want to put forth something you enjoy that balances your strengths in the field.