However, several reports suggest that trade continues, mostly as it did before the new UN sanctions. One Pyongyang businessperson said he felt little impact, other than for those in the minerals trade. Certainly, there was no shortage of consumer goods from China evident on recent CE trips to Pyongyang. 

Essentially, it's a mass mobilization of adults across the country, in nearly all sectors, to work on a variety of projects. Think of it as nationally mandated overtime. The “battle” component is a DPRK cultural manifestation: exhortations often use the term, harking back to the effort needed to win in actual war. In 2013, they had a “harvest battle”, for example. Also, factories or other workplaces are often called “battle zones” or “battlefields”.