Scholarly articles are short(ish) works that are published in scholarly journals. Who are these scholars? Your professors! In addition to teaching they research and write to contribute to the body of knowledge that makes up their discipline. See if you can find some articles that your professors have written.
These sources are meant to be the lens with which you examine primary sources or other scholars that you are putting in conversation. You are trying to identify the conversation that has been going on by finding the (usually) small group of scholars that has been working on this topic. You'll see that they cite each other and build on each other's work.
Scholarly journal articles undergo a peer review process whereby the editor of the journal sends out a copy of the article (with the authors names and institutional affiliations removed) to other scholars in the field. Those peer reviewers, who are also anonymous, read the article, critique, offer feedback, and advise the editor on whether or not the article should be published. The editor then gets back to the author with a decision: rejected, accepted with revisions, accepted with no revisions (pretty rare!). This process of at least two experts reviewing it to substantiate the claims and offer input is one of the things that makes a scholarly journal article "more credible" than other kinds of writing like news writing or trade journals.
Articles+ is what librarian call a federated database, which means that it searches many, many databases across disciplines. It's a great first start if you are not familiar with the databases for a particular discipline and usually returns more than enough results for a writing seminar paper.
The name is slightly deceiving because in addition to scholarly journal articles Articles+ also has book chapters, newspaper articles, e-books, conference proceedings, book reviews, datasets, government documents, media, etc. It, however, would not be my first stop for items other than scholarly journals articles.
Hot Tips for Articles+
The first question really is, do we have this journal? Check the catalog to see if PUL subscribes to the journal in the year that the article was published. If so, you can navigate to the article through the catalog. If not, you can put in an ArticleExpress request to have the PDF of the article sourced and sent to you for free.