The main idea in the Book of Joel is "the day of Yahweh." This expression is found five times in Joel (1:15; 2:1; 11, 21; and 3:14).
The people of Israel looked forward to "the day of Yahweh" as a day that Yahweh would judge the nations around them. But Joel warns that Yahweh would also judge Israel for being unfaithful to him. After judging them, Yahweh will restore his people.
Joel's message applies to the people of God in the church age. For Yahweh says, "I will pour out my Spirit on all flesh" and "everyone who calls on Yahweh will be saved" (2:28 and 2:32, quoted by Peter in Acts 2:17 and 2:21).
The traditional title of this book is "The Book of Joel" or just "Joel." Translators may also call it the "The Book about Joel" or "The Sayings of Joel." (See: [[rc://en/ta/man/translate/translate-names]])
It was common for farmers in the Ancient Near East to experience massive locust attacks. Millions of these insects would come and eat all crops in their fields. Joel may have been describing such attacks in the first two chapters. But because Joel used military terms to describe these locust attacks, he may have been describing enemy invaders who would come and destroy the land and its people.
In the same manner, the drought that Joel described might have been a real lack of rain. Or it might have been a description of either enemy invaders or of Yahweh himself coming to punish his people and the other nations.
Joel prophesied that God will defeat Israel's enemies, rebuild the city of Jerusalem, and rule as victorious king over the whole world. At the same time, God will give his Spirit to all his people, and they will receive messages from him in dreams and visions. (See: [[rc://en/tw/dict/bible/kt/holyspirit]])
#### How should one translate the poetry of the Book of Joel? ####
All of the text in the Book of Joel is poetry, as is represented in the ULB. The UDB, however, presents the text as prose, because many translators will choose to use prose in their versions. Translators who wish to translate the book as poetry should read about poetry and parallelism. (See: [[rc://en/ta/man/translate/writing-poetry]] and [[rc://en/ta/man/translate/figs-parallelism]])