This is how Data Cloud handles an individual's right to be forgotten. It deletes the individual record from the Individual data model object (DMO) and anyrelated records from the data stream objects (DSOs) that are mapped to it.
References:https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_delete_individual.htm&type=5

The relationship between Individual and Contact Point Objects is 1: Many. This means that one Individual can have many Contact Points, such as email addresses, phone numbers, or postal addresses, but each Contact Point can only belong to one Individual. Reference: Data Model Overview

These two features support the need to calculate each customer's lifetime value (LTV) and create breakdowns of the revenue sourced by different channels. Calculated Insight allows you to create complex calculations based on stored data, such as LTV. Segment allows you to create audiences based on different criteria, such as revenue source. References: https://help.salesforce.com/s/articleView?id=sf.c360_a_calculated_insights.
htm&type=5https://help.salesforce.com/s/articleView?id=sf.c360_a_segmentation.htm&type=5

Explanation
This operator can be used to create a segment for a birthday campaign that is evaluated daily. It compares a date attribute to the current date and returns true if they have the same month and day, regardless of the year.
References:https://help.salesforce.com/s/articleView?id=sf.c360_a_data_cloud_segmentation_operators.htm&ty

A window function is a unique requirement of a Streaming Insight query. It defines the time interval for the query to run on the streaming data and the frequency of the query execution. References:
https://help.salesforce.com/s/articleView?id=sf.c360_a_streaming_insights.htm&type=5