Like Journal Citation Report and Scopus, Google Scholar collects and distributes journal level metrics as a way to rank and compare journals. To access these metrics click on the link on the Google Scholar home page titled "Metrics."
The landing page for Google Scholar Metrics shows a list of the top 100 publications across disciplines in multiple languages, despite the fact that they are labeled English language. Most of these top publications are from the Sciences, Physics, Chemistry, and Medical Science.
Clicking on any of the broad categories listed on the left will reveal a list of the top 20 publications in that broad subject area. Each of these primary categories offers a list of subcategories within that primary area. Subcategories range from 16 assigned categories in Business, Economics & Management to 69 subcategories in Health & Medical Sciences. Some subcategories are listed under more than one main category, while others may be a surprise as to where they are assigned. It is worth quickly reviewing each subcategory, especially if you are working in an interdisciplinary field.
Google Scholar also shows ranked lists of the top journals in 8 other languages besides English but these languages do not have subcategories.
You can also search by title keyword within Google metrics to create and compare your own list of journals to compare. For example there is a subcategory under Health & Medical Studies called Gerontology & Geriatric Medicine but if you would like to compare all journals with the word gerontology in the title you can create another list and compare the h5-index and h5-median for those journals.
Google Scholar Journal Metrics Definitions
The h-index was originally developed to measure an author's productivity and impact. In journal ranking the h-index is calculated such that within a journal with an h-index score of 30, there exist 30 journals that have been cited at least 30 times.
The h5-index is the h-index for articles published in the last 5 complete years. It is the largest number h such that h articles published in 2014-2018 have at least h citations each.
The h5-median for a publication is the median number of citations for the articles that make up its h5-index.