what is peer review journal, are they paid by authors
Definition of Peer-review in Wikipedia reads:


  Peer review is the evaluation of work by one or more people of similar competence to the producers of the work (peers). It constitutes a form of self-regulation by qualified members of a profession within the relevant field. Peer review methods are employed to maintain standards of quality, improve performance, and provide credibility. In academia, scholarly peer review is often used to determine an academic paper's suitability for publication.


There is a certain set of information you need to determine whether a journal is peer-reviewed (refereed). See the following useful links:


How to recognize peer-reviewed journal? (From: ASE Library)
How can I tell a journal is peer-reviewed? (From: McMaster University)


There are journals that are called Open access journals, which usually charge a publication cost. The Wikipedia definition of Open Access (OA) journal reads the following:


  Open access (OA) journals are scholarly journals that are available online to the reader "without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself." They remove price barriers (e.g. subscription, licensing fees, pay-per-view fees) and most permission barriers (e.g. copyright and licensing restrictions). While open access journals are freely available to the reader, there are still costs associated with the publication and production of such journals. Some are subsidized, and some require payment on behalf of the author.