Actually, it sounds like the meter/focusing knob side of your camera has the optional mechanism which would be used if you were using 35mm film in the camera. It was part of a kit called the 'Rolleikin' that could be used to switch from 120 film to 35mm film. If you wanted to use 35mm, you would need the other parts of this 'kit' that fit inside the camera. Having the mechanism you have won't bother you when using 120 film.

To use 220 film you would have to have one of the later models of 3.5F or 2.8F cameras. These have a switch on the winder side the moves between 12/24.

TLR Rollei's are great cameras, very refined. Once you get used to the camera it will be second nature to use it. If you do some online research you can find more answers. There is also a book by Ian Parker called 'Rollei TLR User's Manual' that has a lot of info on parts and use of these cameras.