What was your work experience at your previous job in terms of duration?

The question about the duration of work experience at a previous job usually implies indicating the period during which you worked there. For example, you could answer:

"I worked at Company X for 2 years, from June 2021 to May 2023. During this time, I participated in the development of several Flutter projects, which significantly improved my mobile development skills."

If you have no experience, you can honestly mention internships, academic projects, or current studies.