Jay's Treaty was a treaty between the United States and Great Britain that was created in 1794. It was an attempt to settle lingering causes of grievances on the American side.
The US was upset about a number of things. The British were impressing American sailors and seizing American ships that were trading with France. They still kept forts on American territory, supplied Indians with weapons, and encouraged them to resist American settlers. Finally, the British had encouraged thousands of slaves to run away from their owners during the Revolutionary War and had refused to pay compensation.
Because of these things, there was tension between the US and Britain and many of the Democratic-Republicans (who sided with France in Britain's war with France) wanted war. Jay's Treaty averted war for the time being. It got the British to promise to abandon their forts and to pay for ships they'd seized recently. It also opened up Britain to US trade.
But the treaty was extremely unpopular among many in the US. The British did not do anything about paying for the slaves and did not promise to stop seizing American ships and impressing American sailors. John Jay said that he could have traveled all the way across the country finding his way by the light of people burning him in effigy.