The declared objective of this book was to present the key principles and objectives (with the necessary explanations) of the foreign policy that must be conducted by the German government (and that will be conducted by Nazi Germany). Why Adolf Hitler needed 200 pages to do it, is beyond me (IMHO, ten would have been more than enough).
The key objective of the German foreign policy according to Adolf Hitler is to make sure that the German people never ever suffer from undernourishment. He never explicitly stated that but it is obvious that this objective stems from the horrendous death toll of the Great Hunger of 1917-19 caused by the British naval blockade of Germany.
To achieve this objective, it is necessary to ensure that the German soil produces sufficient foodstuffs for the proper nourishment of all Germans at all times. It was obvious that Germany within the 1914 borders would not be able to achieve that objective in the foreseeable future – regardless of the advances in agricultural science (and thus in the productivity of the soil).
Consequently, Germany had no other choice but to wage colonial wars to acquire sufficient Lebensraum (“living space”). According to Hitler, Lebensraum could only be acquired in the East (in Poland, Bohemia, Moravia and Russia – i.e. the Soviet Union). Which made war with these nations inevitable.
To fight and win these wars it was (obviously) necessary to transform tiny Reichswehr into a mighty Wehrmacht. Which automatically meant that Germany had to find the way to get rid of all constraints imposed on its military by the “Versailles criminals”.
Adolf Hitler did not mention it explicitly, but it could be surmised that Germany needed to (1) return all lands taken at gunpoint by the abovementioned robbers and (2) unite all predominantly German lands into Ein Reich. Including Anschluss of Austria and getting back Alsace-Lorraine. The latter obviously meant war with France (which was the mortal enemy of Germany anyway).