Zechariah was a priest. One of the priests had to be chosen to burn incense. They believed that what the lot said was what God wanted. Zechariah was chosen, so he went into the Holy of Holies.
The Priests Realize He has Seen a Vision
When Zechariah was burning incense an angel appeared next to the altar. He was shocked and with fear but he said "Don't be afraid. Your prayer has been heard. Your wife Elizabeth will bear you a son and you are to call him John.
Angel tells Mary that She will Conceive a Baby
Zechariah and Elizabeth wanted children but unfortunately, they couldn't. When the angel said Elizabeth was going to have a child he questioned the angel because they were old. For this, Zechariah was punished by being mute until John was born.
Zechariah Confirms the Prophesy
Zechariah took longer than normal in the temple. When he came out the priests realized he had seen a vision because he kept doing motions because he was unable to speak.
After the fifth month of Elizabeth's pregnancy, God sent Gabriel to Mary to tell her she was going to have a baby. He also told Mary, her cousin, Elizabeth was also having a baby en though she was old, so she went to visit her.
The eighth day after Elizabeth gave birth, the baby was going to be circumcised. Elizabeth said the baby was named John, so the people were confused because no one in the family was named John. Zechariah confirmed his name because he wrote it down on a tablet. Instantly he was able to speak again.