Set the game speed to 50% (Half-speed). Learn the click pattern. Draw the rhythm on a piece of paper if you have to. "Click, pause, double-click, pause, hold..."
Unlike other game modes that involve jumping or flying with gravity, the wave operates on a "hold-and-release" principle: geometry dash space wave
If you need an icon (a "piece" of your character set) that fits the "space wave" aesthetic, you might be looking for: Set the game speed to 50% (Half-speed)