What is a Term?
A term in WordPress is an item within a taxonomy. Terms can provide readers with a more specific description of your post.
More About Terms
Taxonomies and terms have a hierarchical parent-child relationship. Terms are items found inside a taxonomy.
Terms group similar posts and help organize your content. Moreover, a single post can include multiple terms from different taxonomies.
For instance, a post can have the taxonomy Cooking with the terms Baking and Recipes to make it easier to find. However, you may also want to use the taxonomy Desserts and add additional related terms within that, such as Chocolate and Cake.
When users click on a term, they will be taken to a page that lists all posts using that term. You can create terms for your taxonomies using the function wp_insert_term().