What is a predatory Journal?
A journal that publishes a Scientific material without peer review for a financial gain. These journals do not follow the established ethical guidelines for academic works. Jeffery Beall a libertarian from Colorado, USA coined this term and you can refer to his list of predatory journals:
How do you spot a Predatory Journal?
These journals have websites that almost resemble well established journals. They usually do not have an Editor in Chief and if listed you will not be able to contact him. Most of the editorial board members are fake. There turnaround times are very short and will be ready to publish anything you submit. Indian express did a wonderful job of investigating the Predatory publishers in India, please read their article:
Explained: How the pay-and-publish business works:
Indian publishers have been fined by the Federal Trade Commission for 50 million Dollars: https://www.nytimes.com/2019/04/03/science/predatory-journals-ftc-omics.html.