The GF mount lenses are for the Fujifilm medium format camera (GFX 50s). The format has a focal length equivalence (to 35mm film) of 0.79x. Fujifilm launched the format with six announced lenses, three of which were available at first shipment of the body:
In addition, there is an H-mount adapter that allows you to mount old GF645AF lenses (Hasselblad 1) to a GFX 50s. Such adapted lenses can use their leaf shutter up to 1/800. Manual focus only, though the electronic communication between camera and lens is otherwise maintained.