I am a tad confused what you are asking, but will try to answer nonetheless. As far as an interview goes, for any position, you should definitely know information about the company…what they do, approximately how many employees there, general statistics, etc. You should also know the general job description of what is expected, which is usually given when applying, so that your resume can highlight those skills they are seeking.
Beyond that, if you are asking what you should know about the HR field, well that varies. There are many HR positions – generalist, benefits coordinator, etc, etc. Some companies seek individuals for specific HR tasks, while others seek one individual to do all of them combined.
I am with a company as the HR Director (8 years now), and I ‘do it all’. Benefits, hiring/firing, OSHA regs, payroll, compliance, FMLA – the list goes on. It is my job to ensure that the employees are ‘satisfied’, and that the companies needs/standards are being met by each individual thru evaluations, training, etc.
Pros: It is a very rewarding field. I get to know a lot of people, and my job is never dull or boring. It is a field that always, or usually has growth, and is ever changing, which is exciting.
Cons: It is a tough position – walking a fine line between empathy, and the fact that a company needs to run efficiently. It requires long hours, and continually updating yourself on changes, which occur all.the.time. I have updated our policy book a bazillion times because of it. A great example is implementing a Social Networking Policy when those forums became HUGE! They trust I will be able to think of these things with little, or no direction 🙂
It requires organization, multi-tasking, and GREAT communication skills – written, oral and interpersonal. I strongly recommend continually furthering your education with degrees, licensures and certifications.
I hope this helps! good luck!