13.2 % of Na's hits are home runs, nearly twice as high as the KBO league average of 7.4 % (MLB Average is 11.1 % this season, Carlos Gomez is a decent comparable in this regard, not to mention he also plays centerfield, with a 13.3 % ratio. Gomez is a much better runner than Na, not to mention Gomez is clearly playing at a higher level than the KBO). So he seems to be somewhat of an all or nothing hitter, especially since he only has 14 doubles. Here is a GIF of what I believe is his most recent homer:
Here is a screenshot view of his first career KBO homer:
Of course, to compare Na to Votto is not fair to Na, but I think it serves the purpose to show what a great pure hitter does with his hitting mechanics and compare it with what Na is doing. The above screenshots of Na were partially blocked by the opposing pitcher, so here is an angle of Na that avoids the pitcher. This is about as high as his leg kick gets, as he avoids the large leg kick, opting for a more traditional small leg kick as a timing mechanism.
Here is a non home run GIF look at his swing, and a bit of a look at his speed
Even though he is mainly a pull hitter, he can go the other way as well
Defensively, here is a look at his arm strength. He is a converted pitcher that could evidently throw up to 93 MPH and had some success in international play.
Thanks as always to Danny K for the help in gathering information and video for the post. All GIFs and screenshots came from videos from SPOTV's YouTube channel.