Because the people of Moab and Ammon have, in effect, insulted the LORD (verse 10), The LORD will be terrible against them. In particular he will show his superiority over all the gods of the earth. The phrase will be terrible against them (Good News Translation “will terrify them”) may be rendered as “will make them very afraid.” In some languages the idea of “terrify” can be expressed idiomatically; for example, “cause their hearts to fall” or “cause their hearts to shrink.”
Yea, he will famish all the gods of the earth: it is not clear why Revised Standard Version has used the word yea, which is intended to carry emphasis. The Hebrew word usually means “when” (as in New American Bible, Bible de Jérusalem, Jerusalem Bible, and New International Version) or “for” (as in Moffatt and New English Bible). Several modern versions (Good News Translation, Traduction œcuménique de la Bible, Bible en français courant, Die Bibel im heutigen Deutsch) simply omit it here. The verb translated famish literally means “to make thin.” The prophet seems to envisage that, with a lack of people to offer them sacrificial food, the false gods of the heathen nations, including of course the gods of Moab and Ammon, will waste away and in this way come “to nothing” (Good News Translation). Famish all the gods of the earth may be translated as “make the gods of the world (or, the spirits that people worship) so small that nothing is left of them.”
Nations everywhere will then see how futile the worship of false gods is, and as a result all of them will bow down to worship the LORD. Each in its place (Good News Translation “each in its own land”) means that the people of other nations will worship the LORD in their own countries and will not need to go to Jerusalem. In Hebrew the subject of the verb bow down is all the lands of the nations. Since lands cannot bow down, it is clear that the lands stands for their inhabitants. Good News Translation drops the figure of speech and states the nonfigurative meaning as “every nation will worship him, each in its own land.” Of course in certain languages translators will need to make “people” explicit and say “the people of every nation will worship him in their own lands.”
Quoted with permission from Clark, David J. & Hatton, Howard A. A Handbook on the Book of Zephaniah. (UBS Helps for Translators). New York: UBS, 1989. For this and other handbooks for translators see here .