The peer-review process is used by many scholarly journals to guarantee a certain amount of accuracy and quality in the publication of scholarly information. A peer-review panel (or board of editors, or referees) made up of other researchers in the same field will vet the article before it is published. Sometimes the article is sent back to the authors/researchers to be improved before publication.
Sometimes a research article is found to be severely flawed or invalid even after peer-review and publication. Retracting an article means a publication will not longer stand behind it. Reasons for retraction vary greatly, from ethical violations such as plagiarism or failure to disclose conflicts of interest to out-and-out fraud or falsifying results.
Just as there are websites that publish fake information or clickbait to earn profits, there are for-profit publishers of dubious research. Although researchers may knowingly submit articles to some of these publishers in order to pad their credentials, in many cases the publisher is taking advantage of a researcher who believes the publisher is legitimate.