Every profession includes it's jargon, and technical terms. Some of these are self-explanatory other are more arcane. A Gin pole has no resemblance to a swizzle stick. the meaning descends from the original meaning of "gin" which was a device or contrivance. Basically any gadget. "Pole" however is quite literal.
In radio these are used to erect towers. A layperson might guess, or intuitively know that a tower is constructed of very similar modular parts. That it is not a single piece to be erected. The problem is that as tall as they are, it's very difficult to raise, and lower into place the upper portions. In short it provides mechanical leverage.
It is very different from a crane boom for one key reason: It's mounted stationary, to the lower portion of the tower. The basic design is that a pulley is mounted on the top of gin pole, and this is used to pull up segments to a high point where a tower man can position the part. thsi top pulled is called a "rooster head." The hoisting work is done from below so that more precise positioning work can be done above. That being said, these parts are heavy, and if you don;t understand the mechanical principles here you are going to kill somebody. Follow the TIA 1019-Gin Poles Standards.
The lifted segments connected to the running line at multipel points by slings. It is connected at a midpoint called a "tag line sheave" and two or more connections at the top are connected to a "headache ball" to center the load. These points are connected to the load line which bears the weight, and the running line which guides the lift.
The term is nautical in it's origin. The gin pole used in a boats rigging is mounted on a pole perpendicular to the mast, and provides mechanical leverage to quickly raise and lower the mast. It's difficult to do this alone, without one. The terms primary usage is now in tower work, but it's also applied to certain rigs used by arborists and rock climbers.