Message Schedule Logs records track when a Message Schedule is executed and links the Message Schedule to the corresponding Message Runs record that was responsible for sending out the message. Message Schedule Log 
Attachments Tab
The Attachments tab lists any files relevant to the Message Schedule Logs record.
General Tab
Message Schedule (
...
Required)
The name of the executed Message Schedule that is being logged.
Date Executed
The date on which the Message Schedule was executed. This fields automatically populates with the current date upon saving the record if not otherwise specified.
Message Run (
...
Required)
The corresponding Message Runs record that was responsible for sending out the message.