talk is cheap

English

The expression first appears c. 1783 in the play All pleas'd at last.

(idiomatic) It is easy to make boastful or unrealistic statements which are not supported by actions or evidence.
- 1915, Jack London, chapter 2, in The Star-Rover:
  Cecil Winwood accepted the test. He claimed that he could dope the guards the night of the break. “Talk is cheap,” said Long Bill Hodge. “What we want is the goods. Dope one of the guards to-night.”

it is easy to make boastful statements which are not supported by actions

Arabic: please add this translation if you can
Moroccan Arabic: الهدرة ما تشري خضرة (el-hadra ma tašri ḵuḍra, literally “talk does not buy vegetables”)
Chinese:
Mandarin: 说着容易做着难
Finnish: puhe on halpaa
French: c’est facile de parler, un con qui marche va plus loin qu’un intellectuel assis
Greek: αλλού τα κακαρίσματα κι αλλού γεννούν οι κότες (alloú ta kakarísmata ki alloú gennoún oi kótes, literally “squawking is somewhere and hens lay [eggs] somewhere else”)
Italian: si fa presto a parlare
Japanese: 口では大阪の城も建つ (kuchi de wa Ōsaka no shiro mo tatsu, literally “by mouth even a castle in Ōsaka is built”)
Latvian: (vulgar) gudri dirst nav malku cirst (literally “talking smart won't chop you wood”)
Lombard:
Western: se fa a svelta a parlà
Maori: he kōrero i pahawa
Portuguese: falar é fácil
Russian: болта́ть — не мешки́ воро́чать (boltátʹ — ne meškí voróčatʹ), (vulgar) пизде́ть — не мешки́ воро́чать (pizdétʹ — ne meškí voróčatʹ, literally “speaking is not moving sacks”), хва́стать — не коси́ть, спина́ не боли́т (xvástatʹ — ne kosítʹ, spiná ne bolít, literally “bragging is not mowing, [and] the back does not hurt”)
Sranan Tongo: a no babariman e broko pranasi (literally “it's not the noisy ones who destroy the plantation”)