Once you have your Meta tags module installed and configured on your Drupal site, you will want to specify meta tags for all your current and future content.
Taxonomy is a very broad kind of content on your Drupal site, so it is a good idea to use broad, category-like keywords for your meta tags. Simply put, it is how you classify content in Drupal. Many Drupal sites’ first taxonomy is category.
You can also have subcategories of Taxonomy called terms, and terms will have subterms, and so on. It is very easy in Drupal to see all your content in a certain category just by visiting the taxonomy list for a specific term.
The URL for a taxonomy list will be something like this: http://www.yourDrupalsite.com/category/term/subterm.
Here is a quick tutorial on how to edit or add taxonomy meta tag categories, terms and subterms in Drupal: