Zechariah speaks to people who are probably discouraged. They have returned from exile, but they are still ruled by a foreign king, their city and their temple have little of the splendor they had in the days of the great kings like David and Solomon. The prophets have promised a Messiah, but they have been waiting a long time and the Messiah hasn’t come.
But Zechariah proclaims that the Messiah, the righteous king, will come, and that he will bring peace. There will be no more need for chariots or war horses. The king will have dominion “from sea to sea” – it’s not clear what geographic area this encompasses but it’s going to be a big kingdom, big enough that the people will be in no danger from those who have oppressed them in the past.
Jesus offers rest to those who are weary. This rest is not being free of all obligations, but bearing a yoke that is “easy” and “light.” The word translated easy does not mean that little effort is required, but rather means good, kind, suitable, or better (than other yokes).
The image of a yoke might have evoked images of drudgery or slavery, but the word was also used to refer to a rabbi’s teaching, the way of life in obedience to God that he taught his disciples to follow. So when Jesus invites us to take his yoke and learn from him, he wants not just to impart knowledge to us but to guide us in living God’s way.