What does Matthew 20:5 mean?

How much is a day's work in a vineyard worth? Jesus is telling a story that will answer that question: A day's work in the vineyard is worth whatever the master is willing to pay for it, even if you work more or less than other laborers. The point of Jesus' parable, though, is about rewards in the kingdom of heaven for those who work in this life for Jesus' sake.

The master of the house needs laborers for his vineyard in the same way that God uses workers on earth, followers of Jesus, to prepare the way for the kingdom of heaven and to "harvest" those who need to hear the gospel of the kingdom (Matthew 9:36–38). The master in the story hired the first group of workers early in the morning, likely around 6 a.m. They agreed to put in a full day for a denarius. Then the master returned to the marketplace at the third hour, 9 a.m., and hired more workers for "whatever is right." He does the same thing at the sixth hour—about noon—and the ninth hour—about 3 p.m.—agreeing to pay each worker whatever is right in exchange for working for what's left of the workday, until about 6 p.m.

The following verse shows that even all those workers are not enough, though. The master needs still more hands and bodies in the vineyard to get the work done.