They have really strong ground forces.
only because of their huge numbers. their tanks, planes and guns are mostly really old tech from the 50s, 60s, and 70s that they acquired as hand-me-downs from soviet russia and china; that puts them at a big disadvantage in a one-on-one firefight. their tanks and planes are no match for south korea's or the US (remember there is a 30,000+ man force of US soldiers kept in south korea as a deterrent to the north). and their navy is literally just a bunch of small motorboats.
so yeah when it comes to numbers they can overwhelm. but thats their only advantage, and its only for land as well. put their entire "navy" up against just 1 carrier strike group and they're all finished.
they apparently have a crapton of oil reserves tho, if chinese estimates are reliable. that and their large military headcount are the only advantages they'd have in a non-nuclear war. much of their mining and general industrial infrastructure is old and falling apart, and let's not even get started on the massive famines in north korea.