This option allows selection of the team members assigned to the broadcast. The default is all team members for the organization.

In this table you will see Team Member, Re-engage, New Assignments, Total, and Tag Routing.

Team Member is where you select the members of your Organization that you wish to participate in the Broadcast.
Re-engage will only be populated if the Preserve Previous Conversation Assignment option is selected. This column shows the amount of contacts that have previously engaged with the Team Member that are a part of the new Broadcast.
New Assignments shows the number of new messages that will be assigned to an Team Member in the Send Queue.
Total shows the gross number of messages an Team Member will be assigned in the Send Queue.
Tag Routing is utilized to route inbound replies from contacts with a specific tag to specific team members in the organization. For instance, suppose your organization has tagged Spanish speakers with the "Spanish-speaking" tag. Inbound replies from contacts with that tag could be routed to the Spanish-speaking members of the team. Another use case for this feature is if you have contacts tagged as a VIP or Donor -- inbound replies from those contacts could be routed to a specific member of the team ready to handle those important conversations.

Broadcast Routing (Spark)

Broadcast Routing Overview (Spark)