Hi @zeppelin5252 here is a guide which talks about tags as an added level of granularity for categorization. Tags supplement categorization and can further help with grouping transactions which may be related but under different categories.
The guide on Transaction sheet columns describes most Transaction sheet fields. The “Import Tag” however is associated with the CSV Importer. Learn more here.
That’s with respect to tags on the Transactions sheet. Note that you can also add a Tag column on the Categories sheet.