In this chapter Zechariah begins with a message indicating an invasion from the north that would destroy Lebanon, then Bashan and extending down into the Jordan area. He may be describing what happened before when God punished Israel with exile or he may be predicting a future time of punishment. What is obvious is that when it happens the shepherds (rulers) of Israel will be unable to help their people. What is worse, those shepherds will not care.
Zechariah is then told by God to enact the role of a true shepherd. It was a time of instability, indicated by the ease with which three rulers were removed. The prophet also had two staffs, one called Favour and the other called Union. Both eventually were broken and when that happened one was a sign that God's covenant with the nations had been broken and the other was a sign that the nation of Israel itself would divide into the kingdoms of Israel and Judah. If the prophet is not looking back to what happened before the exile, then he is saying that history will repeat itself.
The reward that Zechariah received for his work as shepherd was thirty pieces of silver, which suggests the low reward that the prophet received for his work, indicating that the people thought little of his message, despite some of them recognising his message was from God.
Matthew tells us that the final fulfilment of this enacted prophecy took place when Judas betrayed Jesus for thirty pieces of silver. When the traitor returned the pieces, the Jewish rulers purchased a potter's field with them. They too, although professedly the shepherds of Israel, did not understand the work of a true Shepherd.
Zechariah here illustrates an aspect of the spiritual conflict that believers experience. He became impatient because the people did not respond positively to his message. His response shows that he was affected by the negative response of those who heard him.
The story also shows the importance of referring to previous actions by God in order to describe future actions by him. This is what we do when a sermon is preached or when we study a Bible passage. They remind us of his sovereignty and of the seriousness with which he acts.