Hi, Arnauti, first of all, thank you so much for your detailed explanations in many posts, it helped me understand Swedish language and its grammatical rules enormously. Specifically to this sentence, if both "the tall man" and "that tall man" are correct translation, then why is "this tall man" considered wrong? Or "this tall man" should be "den här långe mannen"? Again, thank you!
Actually, for it to mean "that tall man" you have to stress "den" in spoken Swedish. (Like you would stress "that" in English if there were several tall men you could be referring to.) In that case, "den" functions as a... hm, maybe there's a fancy grammar term for this that I don't know, but let's say a "shortening" of "den där". The equivalent "shortening" of "den här" would be "denna" (or "denne").