Rashi: It means, they commanded to announce. Sometimes verses omit a command, like "Emor la'Na'ar v'Ya'avor Lefaneinu va'Ya'avor" (it means, v'Tzivahu va'Ya'avor).

Malbim (14): Ezra's Beis Din permitted to make Sukos in Yerushalayim, even though it is Reshus ha'Rabim. They announced to permit in Reshus ha'Rabim also in other cities.

Ibn Ezra: Here, the prefix Vov means 'or'. One of them suffices. This is like "u'Mekalel Aviv v'Imo."

Malbim: Some Chachamim expounded like R. Yehudah (Sukah 36b), that the Sukah may be made only from [trees of] the Arba'ah Minim. The verse teaches that one may use myrtle and palm [leaves], but should bring also leaves of olive trees and Atzei Shemen (barren trees - Melachim I, Perek 6) lest the Halachah be fixed like R. Yehudah's opinion ¹ .

Rashi (from Sukah 12a): Alei Hadas are leaves of Hadas Shoteh (the leaves do not come out of the branch in triples). They are proper to make a Sukah ¹ , but not for the Arba'ah Minim. Alei Etz Avos are for the Arba'ah Minim, and so are Alei Temarim (Lulavim).

Ibn Ezra: We know from tradition that Alei Hadas are Alei Etz Avos; the Targum of Avos is Hadasin. Some species have leaves coming out of the branch in triples; this is called Ma'aseh Avos. I saw some in which six leaves leave together - it is most proper to be called Avos (the branch is covered thickly). Some say that one can find seven leaving together.

Malbim: They will not expound R. Yehudah's Kal v'Chomer to require only from Arba'as ha'Minim ¹ .