This is a crowd behavior node, but you can also use it on regular particles (see the Output attribute parameter).
The VOP network ends in a Add Steer Force VOP with parameters/inputs for "Only Add" (boolean), "Steer Force" (float), and "Weight" (float). When "Only Add" is true, the steer force value is added to the existing steer force. When "Only Add" is false, the steer force value is multiplied by the weight and normalized by the crowd solver (see crowd force weights).
When this is off, the node will have no effect. You can animate this to turn the behavior on or off at different times.
Only modify a certain group or groups out of all agents/particles. You can name groups of agents using the Group name parameter on the Crowd Source geometry node.
Available when Output attribute is "Crowd steerforce". This number is used by the crowd solver to normalize and scale multiple forces that apply to an agent.