Kabelvägen was earlier the location of about 20 caches. Those have been removed from their owner quite a while ago (in 2014 I think).
The cache "Kabelvägen M" is a now the first (and hopefully not the last) of a new generation of caches along this nice, about one Swedish mile long gravel-road, which connects the area around N Björke with Thamstorp/Tengene.
The location of the cache "Kabelvägen M" can be seen as the "Midpoint" of Kabelvägen (not exactly), but it is the southernMost point of the entire road.
Alternativly the "M" stands for "Mötesplats" (a defined "Meeting-area" on narrow roads) where the road supposed to be a bit wider, to allow meeting traffic and it is normally marked by the blue and white traffic sign "M".