Second interview with HR?

Hey everyone! I'm getting so excited right now! I had an interview with a hospital last Friday and it went really well. I was in a room with 3 nursing directors from units with open positions and a clinical nurse specialist. I thought I would be nervous as heck with 4 people asking me so many questions but I actually felt very comfortable. Anyway, my references were contacted on Monday and today a woman from HR called me in for a second interview tomorrow. I'm a little curious as to what will go on if anyone has been through this process? I had an interview at another hospital in January and it was the complete opposite. I interviewed with someone in HR and they told me they would forward my application/info to the nursing directors on the units I applied for and they would be the ones who would do a second interview if they were interested. (Needless to say, they were not. )

The woman I spoke to said something like "Depending on what you say and what I say, you could be here for hours." She also said she couldn't give a job offer over the phone for various reasons and told me to bring my driver's license, SS card, CPR card, any immunizations I had for nursing school, etc. Any ideas what this interview might be about? I probably should have asked but I was so shocked and excited that I couldn't think straight. I'm hoping I'll get a job offer tomorrow! I graduated in December, passed NCLEX at the end of that month, and have been applying everywhere since January. I've had only one other interview, as mentioned above, and that didn't go well at all but I think everything happens for a reason. Any input would be most appreciated!