The secondary purpose for a reference check is for a prospective employer to check on your job performance - ensuring that you performed the duties you claim and that you performed them to a high level. Employers will likely want to discuss the claims you have made with you in an interview and, should they be satisfied, then call upon the references you have provided them to verify everything you have said.
Usually you will be required to provide three references to enable a company to perform a reference check - including both personal and professional references. This allows them to gain an understanding of your prior job performance from three different perspectives as well as a better awareness of your personality and attitude. For this reason it is important that you provide a potential employer with valid references who will be able to verify you as an individual as well as you as an employee.
When it comes to reference checks, the majority of companies will no longer provide other employers with much more information than dates of employment and job responsibilities that were performed, which is why it is important that the personal reference(s) you have listed have a solid knowledge of you as an individual. If none of the references can verify more than employment details, the potential employer will not gain any beneficial knowledge on what they can expect from you in regards to your personality, work ethic or attitude around the workplace.
Final considerations for a reference check would be to make sure you inform your references that you are going to be using them as such. Ensure that it doesn't come as a surprise to them when they receive the phone call from the prospective employer, and be sure to thank them for helping you in your job search.