Coles notes ... as I understand it.
The UAW has been trying to get into the "transplant" (import) plants in the southern USA for decades with no success.
UAW membership used to be around 1.5 million. Now it's around 400,000. But they have not downsized their organization and they now have to sustain pension obligations inherited with the GM and Chrysler bankruptcy. They desperately want new members (organize additional plants) to sustain their bloat.
VW management wants a "works council" - basically a joint body of management and workers to address whatever concerns arise - similar to what they have elsewhere in the world. This is the way the unions work in Europe. But this type of arrangement is illegal in the USA, it has to be independent. It's believed that VW management wants this in order to placate the unions in Europe. So VW has actually let UAW into the plant and discussed the matter with them. No one knows what sort of agrreement that they've come to, but the UAW has gotten into some other organizations (notably some Magna plants - another traditionally non-union environment) by agreeing to things that they historically have not done; e.g. a "no strike" clause.
VW has stated in the past that having a "works council" was essential if the Chattanooga plant was to receive additional products. To ME, this makes little sense - but it is likely to placate their unions elsewhere in the world. Certain politicians in Tennessee have been saying exactly the opposite.
So it came to a vote, and the UAW lost. They are now prohibited from trying to organize for another year.
What's it all mean? If VW wants a "works council" they will have to do it some other way. The vote is quite likely not a vote against the "works council" concept, or even a vote against the concept of unionization, but rather it's likely a vote against the UAW specifically. The workers there have certainly seen what the UAW has led to elsewhere. I can't say I blame them for not trusting the UAW to bring in the sort of strangling work rules seen elsewhere.
For the UAW, this is a serious blow. If they cannot organize at a plant which had management not opposing them, and in some ways even encouraging the concept (even if it's different from UAW's traditional model) they have no chance anywhere else.