The Neutrality Act of 1935 was the first in a series of neutrality acts that were meant to detach the United States from the affairs of other countries. These were passed in response to the experiences of World War I. Isolationists felt that the US had been pulled into a war that was not in its interests. They felt that the US had been pulled into that war by people who had an economic interest in the war, not by any sort of more noble factors. This was the basis for the Neutrality Act of 1935.
The act itself was a clear reaction to some of the issues that had gotten the US into World War I. The act made it illegal to sell arms or munitions to any belligerent country whenever the president ruled that a state of war existed. This was meant to prevent the US from getting tied economically to a country that was at war. The law also said explicitly that any Americans who traveled on ships from belligerent countries did so at their own risk. This was meant to prevent the US from getting pulled into war through such events as the sinking of the Lusitania in which Americans travelling on a British ship during WWI (but before the US entered the war) were killed when Germany sank the ship.
Thus, this act was intended to keep the US from taking the same actions that had helped to get it involved in WWI.