
Explanation

The 'Activity is' setting is configured as 'Detected malware in file'. This setting means the policy is applied to files stored in SharePoint or OneDrive.
The Aggregation settings has a 120 minute window. This means that if there 20 detections in 120 minutes, an email will be generated. Therefore, the maximum number of emails generated in 24 hours is 12.
Reference:
https://docs.microsoft.com/en-us/microsoft-365/compliance/alert-policies