라고 하는(what's called: -라고 하다reported speech for NOUN + -는adjective verb ending) 것(thing)은 일단(first, to begin with)놔두고(leave it alone, as it is), 여기(here)까지(up to) 코러스(chorus) 가 많은(many) 곡(song)은, 별로 없어서(because there are not many). It would be easier if I had a full sentence in context, but this is what I get at it from what you posted: If (or Even if) we leave, so called '---' alone to begin with, because there aren't that many (songs) that have a lot of chorus part up to here, ----