In every field or discipline, there are journals that scholars consider highly prestigious and influential. If you ask instructors about the most prestigious journals for research in their disciplines, they can easily name the best journals in their fields.
In addition to prestige, which is difficult to measure, journals are judged by a variety of metrics that look at the impact of articles published in that journal. The metrics usually look at how many citations that papers published in the journal receive over time. The resulting number is called the journal impact factor.*
In the library databases, Scopus and Journal Citation Reports (JCR), you can search for a specific journal to see its impact factor or view journals ranked by impact factor in a specific subject category.
Scopus
1. To view journals ranked by impact factor, select the Sources link at the top of the page. Here you can sort journals by subject. The higher the CiteScore, the greater the journal's impact in that subject. Learn more at the Scopus Tutorials page.
Journal Citation Reports
1. On the home page you can search on a journal name or browse journals by category. The higher the JIF score, the more impact the journal has in that category. (JIF stands for journal impact factor.) Learn more at the JCR information page.
If you need to figure out whether the specific article you're looking at is significant, check out I Do Not Know Whether a Work is Significant in My Field.
* The journal impact factor has received criticism because it is easy to game and not necessarily an accurate measure of quality. See the Declaration on Research Assessment and the European Association of Science Editors Statement on Inappropriate use of Impact Factors.