This is an inline dataview query which means you don’t need to put this into a dataview code block. Just put the command into the body of your note enclosed in single backticks. It will render the Folder that the note belongs to.
For example you can prefix it with a descriptor like below:
This file exists in the following folder: =this.file.folder (don’t forget to enclose the command in single backticks)
You can use inline dataview queries anywhere in your notes.