Role of a postdoctoral research assistant

Context: 4th year PhD student, Social Sciences, UK

Hi everyone, I’ve got a meeting coming up with a PI for a prospective postdoctoral position. But I feel a bit lost about what I need to ask them. I don't want to sound dumb or make of fool of myself in front of them. But the thing is, I don’t really have a clear idea of what postdoctoral research is actually like day-to-day. What are the general expectations from a postdoctoral research assistant? What are the usual outputs of such projects? How are the authorships managed? May be help me with the questions I need to ask the PI as well? Thanks.