They need stimulation and attention. If they're bored, they'll let you know, often by chewing, barking, or other unwanted behavior. Make time to spend with your dog. Make sure all of the people who will be living with the dog are willing to care for the dog, accept the dog into the household, and be responsible for the dog. However, don't expect too much from young children.
Labs are big dogs, and they usually outweigh and far out-muscle young children.
Don't invite disaster by assuming they will know how to get along. Always supervise the dog and the child when together. You should get your dog a physical examination within a week or two of getting it, to make sure everything is OK, to receive advice from your vet about care for your new family member, and to receive any information you need about shots, heartworm preventative, etc.