قال رب اجعل لي آية
He said: "O my Lord! Make a sign for me.''
meaning make a sign that alerts me that the child will come.
قال آيتك أﻻ تكلم الناس ثﻼثة أيام إﻻ رمزا
(Allah) said: "Your sign is that you shall not speak to the people for three days except by signals.''
meaning, you will not be able to speak except with signals, although you are not mute.
In another Ayah, Allah said,
ثلث ليال سويا
For three nights, though having no bodily defect. (19:10)
Allah then commanded Zakariyya to supplicate, thank and praise Him often in that condition,
واذكر ربك كثيرا وسبح بالعشي واﻻبكار
And remember your Lord much and glorify (Him) in the afternoon and in the morning.
We will elaborate more on this subject in the beginning of Surah Maryam, Allah willing