Business Service Management allows users to understand and manage information related to business services. On the one hand, it consumes cloud service status events (like disruption, degradation, maintenance, communication), which are communicated by SAP in SAP for Me and maps it to the corresponding business services. On the other hand, it will be able to consume events from the other monitoring use cases in SAP Cloud ALM for Operations via the Intelligent Event Processing. This allows you to see which business functionality is (or was) affected by a downtime event of a cloud service.
The following graphic illustrate the relationship between the involved components:

Business Service Management has an embedded service level management functionality, where you can define service level objectives for the business services. From the consumed information, Business Service Management can automatically and continuously document the achieved service levels for the business services. Furthermore, Business Service Management includes an Event Calendar, which gives an overview on the events that occurred for the respective business services. This Event Calendar allows the maintenance and execution of customer initiated status events. Business Service Management also forwards the information towards the other monitoring use cases of SAP Cloud ALM for Operations.
What is a Business Service?
A business service abstracts the technical names of services or systems to a name, which can be understood by business users.
The graphic below provides a definition of a Business Service:

Each business service has a name and additional description. It contains a relationship to multiple services or systems. Each business service has a name, a description, and it can consist of one or multiple services or systems. The grouping of these services and systems into a business service is flexible and can be done according to the specific needs and use cases of the organization. Examples of business services mentioned, include the business processes Lead to Cash or Hire to Retire, and various systems related to marketing, training, and development.
Inbound Event Provider
The most important event data source for Business Service Management is the Cloud Availability in SAP for Me,
The following screenshots show SAP for Me and the SAP Cloud ALM Inbound Event Provider:

This service informs customers about upcoming maintenance windows or detected disruptions or degradations for their SAP SAAS, PAAS or Private Cloud services via Cloud Service Notifications. It sends out cloud service notifications that are automatically pushed to SAP Cloud ALM. The supported service types can be found in this list on the SAP Cloud ALM for Operations Expert Portal. If the corresponding service is included in a business service in Business Service Management, then the events are shown in the Event Calendar and in Service Level Reporting.
Business Service Management – Inbound and Outbound Channels
Business Service Management has several additional possibilities to send and receive the data.
Watch this video to gain a better understanding of the inbound and outbound channels in Business Service Management:
Business Service Management – Monitoring Apps
The monitoring apps in SAP Cloud ALM for Operations can show the current status of monitored services and systems as Business Service Management broadcasts ongoing as status events on service or system level to the other monitoring applications. Usually, this information is shown by a small calendar icon in the overview of the other monitoring apps, for example in Health Monitoring. Here, also further details for the respective business service can be shown by the user.
The screenshot below displays the status of a Business Service Management event for a SAP S/4 HANA Cloud service:

Note
Exception Monitoring, Health Monitoring, and Job & Automation Monitoring are suppressing event actions (alerts, eMail notifications, chat messages, creation of tickets, operation flows) during maintenance windows and disruptions in order to avoid double notifications.