This is a very popular option with tobacco companies.
In essence, it is a special glossy finish you can apply to specific areas on your print work to make it shinier. So, for example, you can apply the glossy UV varnish to your logo, or perhaps some specific text to really make it pop.
The overall idea is to create a contrast between the finishing being used for the Fullwrap sticker (MATT or DJEEP SOFT TOUCH© finishing) and the extreme glossiness/vividness of the varnish.
This adds a completely new dimension to your design.
As you can see in the video, the UV glossy varnish is applied over the iceberg, while the fullwrap sticker has a matt finishing over the whole green background.