Nahum describes a messenger bringing “good news” and “peace” to Judah. The verse ties this news to the oppressor no longer passing through, because the wicked are “utterly cut off” (Nahum 1:15).
Nahum closes this section by picturing a messenger arriving over the mountains with public news: peace has been announced. Judah is then told to resume normal worship life—celebrating its appointed festivals and keeping its promises—because the violent oppressor will no longer march through the land. This line functions as a concluding announcement to the opening chapter’s focus on the downfall of Nineveh and the end of its pressure on Judah. Earlier in the chapter the text alternates between describing overwhelming judgment on a hostile power and speaking comfort to those who have been threatened.
Nahum 1:15 presents a vivid scene of public announcement: a messenger is seen coming “on the mountains,” and the news is described as “good news” and “peace.” The verse then directly addresses Judah with two imperatives—keep the festivals and fulfill vows—because the threatening power will no longer “pass through” the land.
A careful answer keeps the immediate passage, the book's argument, and the whole-Bible storyline together, so the question is answered in context instead of as a detached idea.
Start with Nahum 1:15, then read the surrounding section so the answer stays connected to the passage's flow.
15Behold, on the mountains the feet of him who brings good news, who publishes peace! Keep your feasts, Judah! Perform your vows, for the wicked one will no more pass through you. He is utterly cut off.