The Neutrality Proclamation was an announcement of US policy issued by President Washington in 1793. In it, he announced that the US would not take sides in the conflict between Great Britain and France.
Great Britain and France had come into conflict because of the French Revolution. After the French overthrew and executed their king, Britain and a coalition of other countries went to war with France.
Americans in general did not want to take sides in the war. They were too weak to really want to get involved. In addition, they wanted to be able to trade with both sides because much of their economy was based on this trade. Because of these factors, Washington issued the proclamation saying that the US would not take sides.