A champion-sired puppy is one whose father is an American Kennel Club champion. Puppies who are champion sired are thought to be generally more attractive than the most handsome puppies in litters where the father is not a champion.
Having a father that is a champion does not guarantee that all puppies in a litter will be show-quality dogs because not every puppy in the litter will get the best traits from the father. However, it does increase the chances of having a champion puppy. It is also difficult to look at a puppy and know that when it grows it will have the qualities of a show dog.