Elizabeth was never able to bore a child. This was something very big for women back then. She was an elder at this very time and it was very known she would never be able to have a child.
Zecheriah was a priest who would be allowed to go and surpass int the Holy of Holies. He was praising the Lord until an angel appeared making him completely frightened.
Elizabeth is having a child
The angel told him to not be afraid, that for the Lord will give him a child whom will be born and whos name will be John. Zechariah could not believe this since he knew his wife couldn't have a child and was already old.
The child's birth
He decided to doubt and question the Lord towards the angel causing him to have a punishment. He wasn't going to be able to speak until what the Lord said would be fulfilled. As he came out he gave signals and his companions knew he saw something.
Soon enough, Elizabeth was pregnant with a baby. Zacheriah was unable to speak until the day the baby was born. The name was decided and Zechariah wrote down the name the Lord decided.
Zechariah was now able to speak and they were both blessed with a child, John who soon would end up being Jesus' cousin who baptized him.