“Refereed” (also called “peer-reviewed) means that the articles in the journal are evaluated by a group of experts in the field. These experts must approve the articles before they are allowed to be published. These publications have a much higher level of scholarship and are far more trustworthy than non-refereed journals or magazines.
To help you make sure your articles are from refereed/scholarly journals AS you’re searching for them, many databases have limit options. For example:
To confirm that your journal article is from a refereed/peer-reviewed publication AFTER you already have it, check Ulrich’s for the referee’s jersey symbol next to the journal title:
In some journals, particularly those in the sciences, you can look for “submitted/revised/accepted” dates on the first page of the article. These tell you the dates the article went through the various steps of the peer-review process.
Finally, the most authoriative place to look is the journal’s website. Just Google the name of the journal. Look for a description of the journal that says “peer-reviewed” there. Also, look at the information for authors or review policy pages. These will often detail the peer-review process for each journal, including which sections of the journal are reviewed and which are merely edited.