In Arabic language you will see words carrying several meanings. The word “Al-‘Ayn” is supposed to have more than 10 meanings. In the above question, Al-Najm means ‘herb’, keeping in mind that it is coming with the word, Al-Shajar which means tree. “Herb and tree” would make more sense than “star and tree”. However, the context of the previous verse where the words Sun and Moon appears makes someone think that “Al-Najm” means ‘star’. Allama Tabatabai has also preferred to translate this word as ‘herb’ in Al Mizan.