Getting taxonomy name from entity for computed fields
If you have taxonomy id, I'd suggest to do this:

$term = taxonomy_load_term($tid);
$node-&gt;your_field_name[your_language_specifier][your_value_index]['value'] = $term-&gt;name;


if you don't have taxonomy term id you can get it like so:

 $field_name = 'term'; //or what ever your field is named
 $entity_id = 4;//or what ever your entity id is   
 $query = db_select("field_data_field_" . $field_name, $field_name);
 $query-&gt;addField($field_name, "field_" . $field_name . "_tid", "tid");
 $query-&gt;condition("entity_id", $entity_id, "=");
 $result = $query-&gt;execute()-&gt;fetchAssoc();
 $tid = $result['tid'];