A journal endorsement should indicate that you have a particularly positive opinion of the journal in question whether that stems from your experience as a peer reviewer, an editor, an author, or a reader.
The journal browse table can be ordered by endorsements so these can be used to estimate a journal’s popularity and compare them within a field.
Your profile is also linked from the journal detail page of any journal you endorse. Journals you haven’t already endorsed can be endorsed by clicking on the “+” icon in the “Endorsed by” section of the journal detail page. You can remove your journal endorsement from the “My endorsements” page of your private dashboard or by clicking on your profile picture on the journal detail page.