Add fixed tags
A fixed tag is a pre-defined word or phrase that you would like to be applied as a tag when they match the conditions specified in your workflow. In order to add a fixed tag, simply type the tag and press ENTER to add another one. You can add as many fixed tags as you want.
Auto removing tags if workflow conditions don't match
If you want to add a tag when certain conditions are met but you also want to auto-remove the tags when conditions are not met, you can enable the "Auto remove above tags if workflow conditions don't match" setting under the "Add fixed tags" section.
It means that if you want to keep tags in sync with some condition, you won't have to configure two workflows -- one to add the tag and the other to remove the tag.