The Kuvasz is a guard dog that can work well to protect your own children. Unfortunately, the same is not true of other people's children who may come over to play. A dog as large as the Kuvasz is a formidable dog that can cause severe injury to people it perceives as threats. For that reason, the dog is not recommended for families with children, even though it does well with children it considers part of its flock.
If you live out in the country where there are no other people who will disturb the dog, then they do make excellent guard dogs for your children. However, they need to be socialized very early. They will need to be supervised at first with your own children. This large dog is very rambunctious as a puppy and can be too rough on children without intending to be. It doesn't take well to being teased either. Your children have to learn to respect its boundaries so it will learn to love and bond with them.
The Kuvasz pups are clownish snowballs that will learn to warm up to the members of its own family. It will consider anyone in the immediate family a part of its herd. It doesn't have the herding behavior that other herding dogs have, like nipping at the heels and pushing and shoving against people, but it does have a need to guard its charges. It is so overprotective that it can easily forget its training and attack, if it is not kept on a leash when around new people.
If other children come over to play, make sure the dog is put in another room or outside where it cannot see or harm your children's visitors. The dog simply doesn't understand that kids like to rough house and can become overprotective and cause injury.
You will want to get this dog obedience training as soon as possible. It is a stubborn dog that wants to be in charge of everything and needs a dominant handler. It will have to be shown the rules consistently and not allowed to run the household.
If you want a dog to play with your children, the Kuvasz is probably not the ideal pet. However, if you want a dog that can guard your children and not be exposed to other children too much, then it can fulfill this role admirably. Even if it appears to be socializing well as a puppy, this dog retains a mind of its own, as it gets older and much bigger. It is very independent. The size alone can make it difficult to handle and keep from causing injury to children and other household pets.