With this question a potential employer wants to know how reliable you are. This depends on what they mean by dependable. It also depends on the extent of responsibility involved in the position and its requirements.

This may mean being reliable is showing up and doing the work that is necessary as part of the job description. Or it may be keeping information confidential and secure such as a position in cybersecurity or a mental health counselor.

How to answer this rests in understanding the requirements of the position and what you are requires to do. It comes down to expectations. What are the expectations of the position and job performance. Understanding these expectations helps to answer this interview question.