Peer reviewed articles are articles that have been evaluated by the writer's colleagues (peers). The idea with peer review is that the reviewers uphold standards within the field in terms of research methodology, style, ethics, etc.
Most academic databases will allow you to find peer reviewed articles by simply checking a box as you refine your search.
Need a reminder on the peer review process? Check out this video by NCSU Libraries.
In most databases, there is not an easy way to identify which articles report the results of an empirical study. The links below give pointers on finding emprical research articles. There are also links to journals that publish empirical research articles.