A peer-reviewed journal article is a research article published in an academic journal. The article is "peer-reviewed" meaning it is reviewed and accepted as good enough for publication by experts in a subject.
The following links are to what are considered Interdisciplinary Database, meaning they contain articles from many different subjects. You can filter by Subject on the database's page if you would like to see databases specific to a subject.
All of the following database links can be found on the the Databases page
When searching in a Database, you will want to filter for Peer Reviewed (some times it will read as Scholarly) that you can access in Full Text. You will usually find the filters on the Left-Side of the Results page regardless of the database. (see the image below)
(Example from Academic Source Complete)