Hi there mommies! How old is your LO (specially baby boys) when they start talking as in communicate with you?

My no.2 is a baby boy and he talks much earlier compared to no.1 and I believe it is due to his elder sister at home where he can pick up languages earlier. My boy started to call me mummy at 9 months old and talks in sentence (3 to 4 words) when he turned 18 months old.