This UN Vote is merely symbolic. Since we don't even have a peace agreement to begin with !
It's not really symbolic - it would bind Israel to respect the borders laid out in the bill or be in violation of international law, without getting any guarantees of a peace deal that would come with a two-state solution in exchange.
It would also mean that any further aggression from Hamas would likely be a formal act of war.
It would have made the situation on the ground much worse and the US knew what it was doing.