The Smooth Modifier changes the value of one or more stroke/points properties like: location, strength, thickness or UV texture position trying to maintain similar values that make the line fluid and smoother.
Strength of the smooth effect.
The number of smoothing iterations, equivalent to executing the Smooth tool multiple times. High values can reduce the animation performance (FPS).
Combination of stroke/points properties that will be affected by the smooth factor.
Smooth affect the point location.
Smooth affect the point strength (opacity).
Smooth affect the point thickness.
Smooth affect the point UV rotation.