The OBJECT Get placeholder command returns the placeholder text associated with the object(s) designated by the object and * parameters. If there is no placeholder text associated with the object, the command returns an empty string.
You can define the placeholder text either using the Property List, or using the OBJECT SET PLACEHOLDER command.
Passing the optional * parameter indicates that the object parameter is an object name (string). If you do not pass this parameter, it indicates that the object parameter is a field or variable. In this case, you pass a field or variable reference instead of a string (field or variable object only).
If the placeholder is an xliff reference defined using the Property List, the command returns the original reference in the form ":xliff:resname", and not its calculated value.
You want to get the field placeholder text:
$txt:=OBJECT Get placeholder([People]LastName)