As per the Identity Management Base Module Administration Guide, the option "Immediate recalculation of assignments" specifies whether the dynamic role is recalculated when specified properties are changed. If the option is enabled, set the properties for recalculation. E.g.:
The applicable steps can be found here: Calculating dynamic roles immediately if objects change in the section, To enable immediate recalculation of a dynamic role.
In the example above, if the property "EmployeeType" is changed for an Employee, then the recalculation of the dynamic role is triggered. The task "Check single dynamic role" should be visible in the DBQueue. If the Employee meets the criteria for the Dynamic Role (the specified Condition), then the role will be granted.