Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'temasportparma_db.t.id_lang' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by
SELECT t.`id_lang`, t.id_tag, t.`name`, kl.titolo_h1, pt.id_keywords, kl.testo_h1
FROM ps_tag t
LEFT JOIN ps_keywords_tag pt ON (pt.id_tag = t.id_tag)
LEFT JOIN ps_keywords_lang kl ON (kl.id_keywords = pt.id_keywords && kl.id_lang= 5)
WHERE t.name LIKE '%vendita%scarpe%da%calcio%nike%parma%' GROUP BY pt.id_keywords