The J-curve effect is a curve on a graph that starts mid-height, goes down, then swoops back upward, going higher than the initial point.
If you’re having trouble visualizing, thing of the Nike "swoosh."
The J-curve effect is pretty common. Really anything that involves an initial investment up front (loss of funds = initial downturn in the swoosh), which goes toward creating more growth later (the swoosh upward). "Give a little now, get much more later in return" is the message of the J-curve effect.
As when you change time zones and you need to give your body time to adapt...investments, politics, and trade all come with an initial dip that requires time and patience before payoffs are apparent.