From what I understand, "de" really only means "they/them." It seems that the construction "de här" makes it "these" (de här = them here), so there's no room for "here" in that sentence. I'm sure that if you scour Google long enough, you can find a better explanation than this.
That is not quite correct. de does mean they, but it is also the plural form of the article den/det.
However, you're on the right track about de här, de här means these on its own, so if you add 'here' in the translation, you've added something that wasn't present in the original sentence.
Yes, very Southern U.S. sounding. The here is redundant though. Using these instead of those or the already tells you the books are "here". That redundance perhaps emphasizes what is already apparent. The same applies to " These books here are mine"; the sentence works fine without here and correctly translates the Swedish, which isn't placing special emphasis on the here-ness.
You're right, but it's just the Swedish rule when saying 'this object' / 'that object'. You have to use the definite form.. (seems redundant but that's just the grammar). this book = "this (the book)" = den har boken
Scroll to the bottom of: https://www.duolingo.com/skill/sv/Determiners to view a concise explanation and some tables.
- Den (där) boken: That book
- Den här boken: This book
- De (där) böckerna: Those books
- De här böckerna: These books
The "där" is optional in the "den/det/de där" construction, but the "här" is not optional in the "den/det/de här" construction. Pronunciation-wise, if you omit "där", you put the emphasis on "det"; if you don't, you emphasise "där".
Maybe just think of "de här" as a single word.
In English, to change "They are on the shelf" to "These here are on the shelf" we usually shorten it to "These are on the shelf" but Swedish keeps it like "They here are on the shelf". In that sense, the de keeps the meaning you were expecting.