From what I read, they really didn't agree to do anything other than postpone resolving their differences for a while. This, from CNN:
"The statements issued by the two sides, while each positive, illuminated how far apart Washington and Beijing remain despite each country's leader boasting about their strong personal relationship.
The starkest difference was the omission in China's statement of any agreed upon timetable for negotiations.
Also absent was specific mention of what markets China would be inclined to open up -- like agriculture, energy and industrial US products -- three sectors touted by White House Press Secretary Sarah Sanders in her brief statement on Saturday.
Trump repeatedly referred to agriculture -- a flag, perhaps, to US soybean farmers who have been the first to feel pain from Chinese retaliation. "China will be buying massive amounts of product from us, including agricultural, from our farmers -- tremendous amount of agricultural and other products," Trump said.
"Going down the line, you can see what was left ambiguous," said Allen, who viewed the absence of a joint statement as yet another signal of an unclear understanding from both sides.
China's statement also didn't mention Xi's willingness to consider approving a $44 billion deal for Qualcomm Inc. to purchase NXP Semiconductors NV, if the deal was put before him again -- a gesture the White House lauded as an achievement over dinner talks. In July, Qualcomm scrapped the proposed deal for its rival chip maker after waiting nearly two years for approval from Chinese regulators as tensions escalated between the two countries."