I think the matter requires some clarfication. In Arabic you have (a) nominal sentences composed minimally of two nouns, and (b) verbal sentences composed minimally of a verb and a noun. Nominal sentences - because they are composed minimally of two nouns - don’t require a verb “to be” (as an auxiliary or copula) to connect subject and predicate (i.e. as copula or auxiliary) as shown in (A). However, when changing the tense to that of the past or future as shown in (B) and (C) respectively then كَان and س + يَكُونُ are used. (D) is an example where “is” does have an Arabic equivalent in the form of (يكون) . (A) Zayd is a teacher (زيدٌ مُدَرِّسٌ) Zayd is sitting (زيدٌ جَالِسٌ) Zayd is thirsty (زيدٌ عَطْشَانُ) (B) Zayd was a teacher (كَانَ زيدٌ مُدَرِّساً) Zayd was sitting (كَانَ زيدٌ جَالِساً) Zayd was thirsty (كَان زيدٌ عَطْشَانَ) (C) Zayd will be a teacher (سَيَكُوْنُ زيدٌ مُدَرِّساً) Zayd will be sitting (سَيَكُوْنُ زيدٌ جَالِساً) Zayd will be thirsty (سَيَكُوْنُ زيدٌ عَطْشَانَ) (D) When Zaid is thirsty he drinks water (عِنْدَمَا يَكُوْنُ زَيْدٌ عَطْشَانَ يَشْرَبُ مَاءً)

Salam, The short answer is: there is no equivalent of "to be" in Arabic. In nominal phrases, that is, phrases that doesn't require a verb, you can simply append the adjective to the noun to change its meaning. As in your example, " النمـلة صغـيــرة" which means "the ant is small". English is very different than Arabic, they belong to different language families, so it is not safe to assume that the concepts that apply to one would also apply to the other. p.s: for the long answer, please refer to Emir's post! :)