Kernel Base Test: Create node content types and taxonomy vocabularies via configuration?
Here is documentation for using the configuration. 
So for example, if you want to load Tags Vocabulary you will do:

$config = \Drupal::service('config.factory')-&gt;getEditable('taxonomy.vocabulary.tags');
$description = $config-&gt;get('description');


$description contains the description of the vocabulary. In this way, you can load what you want from the yml file.