WordPress at a glance
action is not described

save_post_(post_type) action-hook . WP 3.7.0

Fires once a post has been saved.

The dynamic portion of the hook name, $post->post_type, refers to the post type slug.

Usage

add_action( 'save_post_(post_type)', 'action_function_name_8218', 10, 3 );
function action_function_name_8218( $post_ID, $post, $update ){
	// action...
}
$post_ID(int)
Post ID.
$post(WP_Post)
Post object.
$update(true/false)
Whether this is an existing post being updated or not.

Where the hook is called

wp_insert_post()
WP_Customize_Manager::trash_changeset_post()
wp_publish_post()
wp-includes/post.php 3736
do_action( "save_post_{$post->post_type}", $post_ID, $post, $update );
wp-includes/class-wp-customize-manager.php 2971
do_action( "save_post_{$post->post_type}", $post->ID, $post, true );
wp-includes/post.php 3853
do_action( "save_post_{$post->post_type}", $post->ID, $post, true );

Where the hook is used (in WP core)

Does not used.