/**
 * Implements hook_entity_operation().
 */
function {{ machine_name }}_entity_operation(\Drupal\Core\Entity\EntityInterface $entity) {
  $operations = [];
  $operations['translate'] = [
    'title' => t('Translate'),
    'url' => \Drupal\Core\Url::fromRoute('foo_module.entity.translate'),
    'weight' => 50,
  ];

  return $operations;
}