By saying: طَلْعُهَا كَأَنَّهُ رُءُوسُ الشَّيَاطِينِ (Its fruits are like the heads of the shaitans. — As-Saffat 37:65 ⧉), the fruits of zaqqum have been likened to the heads of the satans. Some commentators have translated the word: الشَّيَاطِينِ (ash-shayatin) in this verse As-Saffat 37:65 ⧉ as 'serpents' since the fruit of zaqqum resembles the hood of the serpent. Therefore, in Urdu and Hindi too, it is called 'nagphan' (hood of the serpent) for this very reason. But most
commentators have said that the word: الشَّيَاطِينِ (ash-shayatin) here should be taken in its well-recognized sense. Thus, it would mean that, in its ugliness, the fruit of zaqqum is like the head of the satans. Now, let there be no doubt here that nobody has seen the Shaitan, why then, would something be likened to him? The reason is that it is an imaginative simile. Speaking metaphorically, things ugly and grotesque are commonly likened to Shaitans, Jinns and ghosts. The purpose is only to express an extreme degree of ugliness. The simile used here is also of this very nature. (Ruh-ul-Ma’ ani and others).
The sense of the rest of the verses is clear from their translation.