Hose bibb is defective. Somewhere at some point a hose was left on it during the winter/freezing months possibly and water could not escape the faucet, thus the reason it froze and broke.
When you take that faucet out, 2-3" behind that brass spigot you will find a belly in the copper where it bulged out and broke.
Replacement is the only way to go; the only prevention is having nothing attached to that faucet so it can drain. Otherwise it loses its protective features altogether.