The Labernard is a mixed breed dog that offers the best of the two parent breeds' more appealing traits. These are big dogs that are well-suited for a variety of tasks but may not be as good at any one of them as their parents. That's not a bad thing, however, as their parent breeds have specific tasks and less versatility elsewhere.
Still, these dogs are intelligent even if they are a bit bullheaded. They may be difficult to train for those who are not experienced, patient, and confident. It will take a lot of patience on your part as well as perhaps a couple years to fully and properly train the average Labrador St. Bernard mix.
The playfulness of the Lab and the wanderlust of the St. Bernard will mix to prompt the Labernard to be all about fun. They will be loyal, and they will work, but they would prefer to explore and romp in a way that may not exhibit the typical type of loyalty and work of most dogs.
The ways this hybrid dog will exhibit his appreciation is less through obedience than via playfulness and a desire to explore. They will also like to be a bit "lazy" if allowed to be, as they will want to both reserve their energy (like A St. Bernard does) as well as be by your side when they are inside (like a Lab).