roles

$roles = Role::loadMultiple($user->getRoles());

foreach ($roles as $role) {
 $label = $role->label();
}

 $role_object = Role::load('authenticated');
 if ($role_object) {
   $role_object->grantPermission('mymodule write messages');
   $role_object->save();
 }

$roles = $this->entityTypeManager->getStorage('user_role')->loadMultiple();

$current_user = \Drupal::currentUser();
$roles = $current_user->getRoles();
if (in_array('editor', $roles, TRUE)) {
  //
}