The Kuvasz has a booming bark befitting this large dog. It is an excellent watchdog and will be on watch all night long. This can be great if you live out in the country, but hardly ideal if you live in the city. The Kuvasz is not a dog that does well in urban environments for this reason. Instead of using its great watchdog instincts for protecting your property, in the city you will probably end up with the animal control people being called every time your dog becomes a noise nuisance.
The dog does use his menacing bark to warn off strangers from your property. The problem is that he will bark at just about anyone and anything. It can be a small animal that crosses your backyard or a dangerous intruder. The dog doesn't really differentiate when to bark or what times are appropriate for it.
Some people train their puppies to bark on command. The reasoning is that once the dog has a command for barking, it will be easier to teach it to stop barking too. While that may be possible, the dog was bred to be a watchdog and not barking would be contrary to that function. You may be able to get it to bark on command, but its not likely you can get it to stop barking at all hours of the night.
You can try to use bark collars, but again, the dog is a noisy barker. It is like punishing it for something it was bred to do. The idea thing to do with a Kuvasz is to not have one in the city or urban environments. This is really a guard dog for the country.
Do realize that the temperament of each dog is different. You may find a Kuvasz that is not as high-strung and mellower than the typical Kuvasz. You may even be able to train it to be quieter than the average Kuvasz. This is possible with any breed that has a wide range in temperament. Just be aware that the bark was considered to be a positive for people who used the dog for guard dogs and for herding sheep. It was a vital and effective tool when performing these functions. If now, the dog is meant to be a pet, this may be asking a lot from a dog that has years of breeding as a guard dog. It will require patience on your part and some very understanding neighbors. Barring that, keep the dog in the country where the bark won’t annoy anyone except the chickens. Then, you will be happy that you have such a wonderful guard dog in place helping to guard your livestock and keep the predators away.