What is the "Greeting" Field Used For?
From Support Wiki
When completing the personal and contact information for your representatives, the Greeting field can be used to store the common name used by your representative.
For example, if you have a representative named Robert, you could enter “Bob” in the Greeting field. Then when sending out a communication, you could specify Greeting as the mail merge in the salutation. Example: “Dear [Greeting],” which would say “Dear Bob,” when it would be printed/emailed.