Short answers, pulled from the story.
The agreement aimed to establish a period of peace between Poland and Germany by excluding war between the two countries. Józef Piłsudski sought this declaration due to concerns over France's Maginot Line construction which left eastern allies like Poland on their own without guaranteed support.
Hitler denounced the declaration unilaterally on the 28th of April 1939 during an address before the Reichstag. He renewed territorial claims in Poland citing the Anglo-Polish alliance as justification for the denunciation.
A détente between Poland and Germany began in early 1933 through secret talks led by Józef Beck. Hans-Adolf von Moltke interpreted a veiled proposal for direct contact made by Beck in April 1933 as a key step toward rapprochement.
To allay fears of war, Poland renewed the Soviet-Polish Non-Aggression Pact on the 5th of May 1934. This renewal extended until the 31st of December 1945 despite repeated suggestions from Hitler to form an alliance against the Soviets.
Anna Cienciala wrote in 1975 that the pact formed part of a policy of equilibrium seeking to preserve independence by balancing relations with both Germany and the Soviet Union. Later historians have been less critical of the agreement than earlier critics like A.J.P. Taylor.