"Peer-review" means that an article is reviewed by other experts in that field (the author's peers) before the article gets published. This means that if an author writes an article on juvenile counseling, other experts on juvenile counseling will review the article to make sure it’s acceptable to be published. The peer review process ensures that the research described in a journal's articles is credible and high quality.
Use the peer-review filter while searching library databases to limit your results to peer-review only. You can also check a journal's publishing standards and process, usually listed on their website.