HOW? I looked all over the menus, pop up menu too.
Assuming you’re talking about XFCE’s Thunar file manager, it’s either File > Terminal or Terminal in the context menu for a directory.
If you don’t already have it for some reason you can add it in Edit > Configure custom actions. Create a new entry that runs your favorite terminal app and give it %f as the parameter that will take the value of the directory you want. Please make sure to select only “Directories” in the “Appeareance conditions” tab.
You can create other custom actions too, for example I use zenity --question && shred -fu %F to shred and remove a file after asking for confirmation.