Peer-Reviewed, Scholarly, or Refereed journals contain articles written by experts within a discipline of study. Before being published, the articles are reviewed, or checked for quality by other experts in that same field. Think of this as quality control for the information. The review process is often times double-blind, meaning that the submitting author doesn't know the identity of their article's reviewer, nor does the reviewer know that identity of the author which helps to ensure that the review process is unbiased.
To determine whether or not a publication is Peer-Reviewed:
Check to see if the journal is found in the Library's Periodicals by Title List.
Search for your desired title.
Once you've searched for your publication's title. Locate your publication in the result list. When you click on the publication title, you'll be taken to a page that describes the publication.
If you are unable to locate your journal in the Periodical by Title search, find your publication's website. On the website, there may be information about the publication's peer-reviewed status located under the publication's "About" section or within author submission guidelines located on the website.