A Marketing Cloud admin has been asked to Include Sales Cloud data in their queries.

Synchronized Data Sources is the feature that would allow this functionality. Synchronized Data Sources are data sources that allow marketers to import and synchronize data from Salesforce CRM objects into Marketing Cloud data extensions. Synchronized Data Sources can be configured with different settings, such as sync frequency, field mapping, and filter criteria. Synchronized Data Sources enable marketers to use Sales Cloud data in their queries and other Marketing Cloud activities.