When browsing the list of tags on a site, a number is shown next to each tag indicating how many questions have that tag, e.g. “sometag × 42”. If there is a single question with that tag, no indication is shown. If the tag is a synonym of another tag, or if the tag has no questions and is scheduled for deletion the next time the cleanup job runs, no indication is shown.
Please visually distinguish tags with a single question from tag names that are synonyms and tags that are scheduled for deletion. This is very useful information when reviewing tags.