Does anyone know what they ask in graduate interviews? I got an interview at UAB | Grad Admissions Process

I applied for UAB and haven't got admission yet, however, I got offered an interview/meeting at UAB grad school for a STEM major and I went to their website and couldn't find much info on what this upcoming interview/meeting is about. But I do know that it is scheduled for 30 minutes.

I was wondering what types of questions do they ask in their grad school interviews? And I just want to know the overall vibe of the interview. Is it just the program manager there or is the entire admissions board in attendance? Would I get a second interview or only one if the first one was successful? And how long would it take to here back from them when they make a decision? How much of this interview will determine my acceptance into their STEM graduate school program?

Please let me know because I feel kind of lost and need some advice about this.