You can do something like this:

$referenced_titles = array(); 

foreach ($item2 as $indice => $values) {

  $entity_field[]['value'] = $values->field_nombre_2['und'][0]['target_id'];
  // use node_load($nid) to load the node. 
  $referenced_node = node_load($values->field_nombre_2['und'][0]['target_id']);
  $referenced_titles[] = $referenced_node->title;

}

You can do something like this:

$referenced_titles = array(); 

foreach ($item2 as $indice => $values) {

  // use node_load($nid) to load the node. 
  $referenced_node = node_load($values->field_nombre_2['und'][0]['target_id']);
  $referenced_titles[] = $referenced_node->title;

}