What does Luke 1:23 mean?

Under Old Testament Law, priests came exclusively from the tribe of Levi, and only from the lineage of Aaron (Exodus 40:15; Numbers 25:13). Aaron's descendants were organized into 24 "divisions," who rotated through week-long periods of service in the temple (Luke 1:8). One such priest is Zechariah. He was recently chosen to offer one of the two daily sacrifices of incense (Exodus 30:1–8; 40:26–27). While performing the rite, alone in the Holy Place, he was visited by the angel Gabriel and given happy news: he and his wife (Luke 1:5–7) will finally have a child of their own (Luke 1:11–17).

Zechariah's first response to this news, unfortunately, was doubt it could be true (Luke 1:18). As a result, he was temporarily rendered mute (Luke 1:20) and apparently deaf, as well (Luke 1:62). Scripture does not say how much he was able to tell others about his encounter (Luke 1:21–22). Most likely, he told his wife, Elizabeth, as much as he possibly could when he completed his term of service and he was able to return to her.