What little information is available suggests that while North Korea boasts a high literacy rate (claimed to be nearly 100%), the quality of education is significantly lower than in other comparable countries. The curriculum is heavily focused on propaganda and glorification of the regime, often at the expense of critical thinking and practical skills. Resources are also limited, especially outside of Pyongyang. Therefore, while the *years* of schooling might appear high, the actual educational attainment and knowledge gained is likely much lower than suggested by raw enrollment numbers.
In short, there's no reliable answer to the question of "average education" in North Korea in terms of a quantifiable metric like years of schooling equivalent to other countries' educational systems. Any number presented would be highly suspect.