https://player.vimeo.com/video/750283318?h=6d03aaa607&badge=0&autopause=0&player_id=0&app_id=58479
There are two types of operation: Velocity (the default) and Force.
In this mode, the modifier will take complete control over the speed of the particle.
nxAttract Type set to Velocity.
There is also an effect over the speed of the particles, but the Force mode can be used in conjunction with other modifiers to contribute to the final result.