question

It's a little confusing, but the condition is the condition to block a traveler. From Divider Path Properties:

Check this box to make a barrier conditional, and define the condition that is required for the barrier to be applied. When a barrier is conditional, its condition is reevaluated at the beginning of every travel task. If the condition returns false (0), then the barrier will not be applied in the route calculation algorithm, and the traveler will travel as if the barrier did not exist. Conditional barriers let you define certain barriers as only applicable for certain travelers, or based on certain model conditions.

So the default rule (traveler.Type == 1) will block all travelers who have a Type label of 1, but everyone else can walk through the barrier.

Here's an example using your Dept label from earlier, the divider on the left blocks everyone but Dept 1 (traveler.Dept != 1) and so lets Dept 1 people through. The divider on the right does the opposite blocking all but Dept 2.

BarrierConditions.fsm