there are some general questions employers may ask in an interview. there are articles online on how to prepare for them. but, going into the unknown will give anyone anxiety or be nervous. in that regard, you can go in with no expectations, and just respond with the questions they do ask you.
they will rarely hire people on the spot these days. as they often go through multiple candidates and sometimes multiple rounds of the same candidate before offering the position. so the worst that will happen is you'll get an email or phone call from the employer saying you didn't make the cut. then just use the experience and improve from it for the next one.
bring a notebook with you. not to the meeting, but when you're done in the car before you leave and write down what happened. what questions they asked, who was there, their titles, etc. that way you can see some pattern for the interviewing process.
ask for your school for help. talk to a counselor or adviser. they should have resources for students looking for work. including improving your resumes, and maybe help prepare for interviews. see if they have job fairs too. where companies from all over can send recruiters to your school and you just apply there on the spot and ask questions. some will give interviews, some will take your info to schedule an interview later.