V is for the self timer, x is for x flash sync and m for m sync, X sync is for electronic flash and m would be used if you were using flash bulbs. I would suggest that you never use the self timer on this or any classic camera as if there is a weakness in the prontor or compur shutters it is the self timer, and should it stick then it would render the shutter un usable and mean a trip to the camera service shop, so leave it set to the X setting and leave it there,I have a number of older Voightlanders, including a Vitomatic 11a, and they are terrific cameras if you can live with a fixed lens, one tip I have found is to set the exposure meter with these cameras to over expose by 1 stop, and check that it is working against a known exposure meter, other than that do what I do and enjoy using cameras from a golden age which we will not see again.
Richard