Taxonomies in WordPress are ways to classify content, like categories and tags.
You could have custom taxonomies, often created by a plugin like Advanced Custom Fields. These taxonomies could be for things like: Author, Region, Type, Product Line, Color, etc. Basically any way you’d like to have organized buckets of content.
Each item in a taxonomy is called a “term”. So if you had a taxonomy for “Colors” then the terms might be “blue”, “green”, “red”, etc.
SearchRovr uses taxonomies to organize and filter search results more effectively.