Yes a dogs hair will eventually start growing back after you shave it off.
Dogs shed their hair all the time and new hair grows back in place after the dog loses it's hair so when you shave the dog new hair should come back soon.
It can take a month to start seeing new hair grow back on the dog and then it can take another 3 to 7 months for the dogs hair to fully come back.
But some dogs hair may grow back faster depending on the dog breed.