This filter is found in
It displaces the pixels of the active layer or selection to waves or ripples reminding a reflection on disturbed water.
Antialiasing: This improves the scaled look the image borders may have.
Retain Tileability: This preserves the seamless properties if your image is a tile pattern.
That's the Hozizontal or Vertical direction of waves.
Because of ripples, that are a pixel displacement, some pixels may be missing on the image sides:
With Wrap, pixels going out one side will come back on the other side, replacing so the missing pixels.
With Smear, the adjacent pixels will spread out to replace the mixing pixels.
With Black, the mixing pixels will be replaced by black pixels.
These options are self-explanatory
Sawtooth
Sine
The Periode is related to wavelength (0-200 pixels)
The Amplitude is related to wave height (0-200 pixels).