If you are searching Web of Science, there are two ways to find out the impact factor of a journal. The impact factor is a measurement that takes into account how many times the journal's articles are cited, and may reveal something about the journal's reputation.
1. Go directly to InCites Journal Citation Reports, enter the journal title in the search box on the left, and click on search. On the left click on RANK. Q1 means 1st quartile, Q2 means 2nd quartile, etc.
2. Search the Web of Science Core Collection by keyword/topic. Click on the journal name in the search results, or click on View Journal Impact in the article description. You'll see the impact factor, rank and quartile for the journal in the various categories to which the journal is assigned.