The mouthpiece part goes on the bowl, the golden pan with the bud in it is heated from below to vaporization temps with a torch lighter. One of the tastiest, most efficient vapes I know, albeit with a bit of a learning curve as there is no indicator for when to stop heating, so it becomes a bit of a timing game to get it just right.
There's a bunch of great options for butane powered vapes these days, definitely a very interesting subsection, I like the manual action.
Battery powered also has its place though!