As to what you could bring, it's hard to answer without knowing just what kind of experience you
do have. Bring a resume, for openers. Sometimes work that you've done, which doesn't seem to have anything to do with secuirty, does, in fact, relate to security concerns. For example, did you ever work in retail sales? That means you have experience dealing with people and are accustomed to watching out for potential shoplifters. That's security experience.
Years ago I got a job as a gallery guard at an art museum. What made my employers think I knew anything at all about museum security? Why, the fact that I had done contract work as a foreign language interpreter for the US State Dept. I had, on several occasions, accompanied visiting foreign police officers to their appointments with American law enforcement agencies. That was considered experience.
If they're calling you in for an interview, you're more than half-way to having the job. Be presentable and expect such questions as "How do you handle stress?" (Don't say you get drunk or stoned to handle stress

) and "How well do you get along with other people?" Site security usually involves being firm but very polite to everyone and having a sharp eye for anything out of place.