Questions are to Data Science what User Stories are to Applications. That's it.
When developing user-turned applications, user stories is a tool to make sure the implemented user interface is aligned with the users expectations. They focus the development towards what is important and allows to filter out tasks that are not supporting the user stories.
The same is the case for data science: A team puts forward a number a questions. Some grand questions, and some smaller one that lead to the answer to the grand one. Having those questions in mind always aligns the data scientist with their stakeholders.