This is called a merge field.
You can create one from layout mode by going to "Insert" - "Merge Field"
Or you first create a text field and then do "Insert" - "Merge Field" (or Crtl - M on windows)
You can combine a merge field with other text. Like on a letter:
Dear <<Title>> <<LastName>>
The down point on a layout is that you can't perform a find on a merge field.
I always use merge fields to put a calculated FullName field That combines the Firstname and the Lastname on the top of a layout.