My dog is mating with another dog?

My dog is 11 months old.She's going to be 1 year old on august.This morning,I was about to go to school but My sibling saw her mating with another dog.And I thought she's still a puppy and I thought that her age is not suitable in mating.I don't if she's a dog already...My other sister is going to school she's riding a school service to go to school but she didn't locked the gate and my dog pushed the gate and she mated with the male dog..Is 11 months already a dog?And is it hard to take care a puppy?