What does Luke 19:28 mean?

This is a summary statement for the next large section, sometimes referred to as the "presentation of Jesus in Jerusalem" (Luke 19:28—21:38). The previous section, sometimes called the "travelogue to Jerusalem," began, "When the days drew near for him to be taken up, he set his face to go to Jerusalem" (Luke 9:51). During the travelogue, Jesus prepared His disciples for His death, resurrection, and ascension as well as for their commission to go on and build the church. Now, His arrival is imminent.

For Jesus, the road to Jerusalem has included miracles, parables, acceptance, and rejection. The week ahead will be eventful. First, a great crowd will accompany Him up the hill to the Temple Mount, crying His praises as king (Luke 19:36–38). But along the way, Jesus will catch sight of the city of Jerusalem and weep over its coming destruction by the Romans (Luke 19:41–44). Next, He will enter the temple courts and find them filled with merchants and venders hawking items visitors need for the Passover in the area reserved for faithful Gentiles (Luke 19:45–46).

The days will continue with Jesus arguing with the religious leaders. Women will anoint Him for His death. Jesus will take time to reinforce to His disciples that a spiritual war is coming. They need to be prepared and keep their eyes on God and His coming deliverance (Luke 21:5–38). And then, Luke records the Last Supper and the cross.

"These things" are in the same theme. Jesus had just told the parable of the ten minas (Luke 19:11–27). The Jews will have all the information they need to decide if He is their Messiah. Only those who commit to Him will live in His kingdom.