View this short video from NCSU libraries that explains the peer review process.
Many journals in the sciences have a metric called the "impact factor." The impact factor is a number is usually displayed on the journal's home page, like this:
The impact factor is calculated by Clarivate (see also here), a company that produces Web of Science and other information products. The impact factor is viewed as a measure of the relative importance of a journal within a field of study. A journal with a higher impact factor number is viewed as more important and prestigious within a field.