적 is a noun 1. a point of time, when ex) 그는 어릴 적에 시골에서 자랐다 He grew up in the countryside when he was a child. 2. experience ex) 서울에는 한 번 가 본 적이 있다 I've been to Seoul once 여섯 살 means "six years old" 여섯 살적 means "When I was six years old" ~한 적이 있다 means "have experience in something" 본 적이 있다 means "I have experience in seeing" or "I have seen" 제목의 means "with a title". It is same to 제목을 가진 체험하다 means "expericence" 체험한 means "which is experienced" 체험한 이야기 means "story which is experienced" so "True Story" 여섯 살적에 나는 《체험한 이야기》라는 제목의, 원시림에 관한 책에서 기막힌 그림 하나를 본 적이 있다 means When I was six years old, I have seen a magnificent picture in a book about the primeval forest with a title of "True story". Following is the translation of same sentence: In Enlish book, Once when I was six years old I saw a magnificent picture in a book, called True Stories from Nature, about the primeval forest. In spanish book, Cuando yo tenia seis anos vi en un libro sobre la selva virgen que se titulaba "Historias vividas", una magnifica lamina.

Thank you very much! This was very helpful! Thank you for also letting me know that 체험한 이야기 has a vague meaning anyways, that gives me some relief for not being able to really understand it! Thanks for your time! :)

And about 체험한 이야기. Because it's like the name of a book it can mean different from what I wrote above there. It really depends on. From the view of a native speaker of Korean, even I can not be 100% sure that I understand the meaning of it.

여섯 살적에 나는 《체험한 이야기》라는 제목 의, 원시림에 관한 책에서 기막힌 그림 하나를 본 적이 있다." Ok, it's pretty much challenging question haha. For starter, 적 in 6살적에 means around or about 6 years old and it's not really a formal way to speak or old people can use that while speaking. Second 적 in 본 적이. 적 is usually reffering to experience that you've done before. Yes it is just like the grammar "Have p.p." In English. However in this sentence, it just makes it clear that it happens in the past and it can imply that you're going to talk about further details on it. Like, 예전에 한국 음악을 들어 본적이 있어. 그런데 내 취향은 아니었어. Ok I'll try translating it! When I was around 6 years old, I once saw a spectacular painting from a book on primeval forest called ' The stories from the experience'. I hope i'm able to help you out with this.