Tags are used to group elements of content together. Every Topic can have a Tag applied (in Content Hub) and then every guide can have a Tag applied (on the Guide specific content tab). When the Tags between a Topic and a Guide match, then that topic shows on that specific guide. Simple!
If you only have a single guide then you will only need a single Tag and likely won’t need to do anything else as this will be automatically set up for you.
If you have multiple guides you can create different Tags and assign different content to them. For example, a local area guide can have its own Tag and be used just for properties located in a particular area. Then, when you update any content attached to a Tag, it will automatically update all the guides that are associated with that same Tag. It's all explained in the video and article below:
Video: How to use Tags for your second guide
Note that only topics can be given Tags, you can’t give a Category or Subcategory a Tag since they don’t hold any information (text or media) and are only used for organising your Topics in the menu of the guest view. Use the Edit Topic screen, accessed by clicking on the topic name in Content Hub, to update the Tags for each topic. You can also update Tags in bulk as explained in this article.
Further details about setting up and using Tags can be found in these articles: