How I can get custom post type taxonomy description? My post type is 'release' and taxonomy is 'release_category' , what code should I use?
If you already have the term_id
term_description( $term_id, $taxonomy ) : https://codex.wordpress.org/Function_Reference/term_description
term_description($term_id, 'release_category');
If you only know the post id
First you must get the post taxonomies with wp_get_post_terms( $post_id, $taxonomy, $args ) : https://codex.wordpress.org/Function_Reference/wp_get_post_terms
$taxonomies = wp_get_post_terms(get_the_ID(), 'release_category', array('fields' => 'all'));
foreach($taxonomies as $taxonomy) {
echo $taxonomy->description;
}