The Great Pyrenees is also known as the Pyrenean Mountain Dog. This breed was used for a variety of work in the region including herding and personal protection.
They are generally very friendly and even-tempered dogs. With proper socialization, they will get along well even with strangers. However, they are very territorial and tension with other pets is to be expected.
The Great Pyrenees is also known for being very vocal. This could come in handy if you want to keep it as a watchdog. If not, you will have to invest time and effort training them to stop the habit.