Broadcast on Contacts is a preview of bulk messages that were sent to the contact. If you search for a contact on the Contact's Menu, You can see the list of all the broadcast that was sent under the broadcast feature.
Click Contacts Menu
Choose and Click a contact.
Scroll down and click the broadcast dropdown to expand
Click any broadcast you want to view
Also, you will see the name of the broadcast on the activity footer of the message.
Filter Contacts through Broadcast Attribution
In the Contacts menu > Click Filters Button
Under Attribution > Click and Select Broadcasts (You can select multiple broadcasts at the same time)
The Contacts overview will show you ALL the contacts that received the Broadcast.