What is a DOCVARIABLE in word

How do I make it display in my word document:

Insert->Field->Category:DocumentAutomation->Field Names:DocVariable->Field COdes Button-> Then enter the name of the variable.

You can use the Microsoft Visual Basic for Applications Variables collection to set and retrieve the contents of a string variable in a Word document or template.

Also, you can use the DocVariable field to retrieve the value of a document variable after it has been set to display within a Word document.

Source: How to store and retrieve variables in Word documents

Sub GetSetDocVars()

Dim fName As String
fName = "Jeff Smith"
' Set contents of variable "fName" in a document using a document
' variable called "FullName".
ActiveDocument.Variables.Add Name:="FullName", Value:=fName
' Retrieve the contents of the document variable.
MsgBox ActiveDocument.Variables("FullName").Value

End Sub