2) これは日本で売らない本です。
"They don't sell this book in Japan."
Although I believe うらない translates to "will not," "don't plan to," "are not going to" etc., a future construction only, as toritoribe and I translated above.
In a vacuum, "Will not", "Don't plan to" don't work in this case - it's more information than is implied. If placed in context, they could mean this, but it is not in this case.
This is where Japanese relies on the context so much. If the publisher of a particular book was asked:
この本を日本で売るつもりですか？ - "Do you plan to release this book in Japan?"
売らない - "I don't plan to."
However, if you asked a friend if they were selling it:
この本は日本で売るんですか？ - "Do they sell this book in Japan?"
売らない - "No, they don't."
In general, I feel it's better to think of word meanings in their barest form, and then contextualize them.
And there's no "they're" as an intentional subject to do the selling. As toritoribe explained, 売っていない expresses more a state of "not being sold" or "not for sale."
It is true, but the context doesn't give it in Japanese. It is common when speaking in English to provide this context, and so a more natural translation will have these elements placed in where they are expected by the listener.
A common way of asking this in English is "Are they selling this there?" for "Is it sold there?".
The fact is, simple translation is a one-to-one mapping, but good translation is many-to-many.
Through a simple, direct translation, there is no natural Japanese phrase that would translate to "They are selling this book in Japan." Does this mean this phrase should never be used as a translation? Of course not! It is a sentence that matches the tone, intent, and naturality of the source material. Most of the time, a combination of these factors is far more important than the pure meaning.
</end translation rant>
