Explanation
The _Subscribers data view contains information about each subscriber in an account, such as subscriber key, email address, status, and business unit ID. The_BusinessUnitUnsubscribes data view contains information about each unsubscribe event for each subscriber in a business unit, such as subscriber key, business unit ID, and unsubscribe date. By using these two data views, the data team can find subscribersin their Marketing Cloud account and their unsubscribe data for child business units. References:
https://help.salesforce.com/articleView?id=sf.mc_as_data_view_subscribers.htm&type=5https://help.salesforce.c