At the bottom of your campaign tool Content screen, you have the option to add tags to each campaign action:
As you would with any other tagging system, just separate tags with a comma, like so:
There are a couple of cool things that you can do with tags on New/Mode campaign tools:
If you’re syncing your campaign tool with a CRM that supports tags, the tags you enter in this field can be added to CRM data.
You can enter tokens as tags, which will then be powered by the data from submissions: