What does Mark 14:16 mean?

Jesus has asked Peter and John to prepare the Passover meal for Him and the disciples (Luke 22:8). They go into Jerusalem and find a man carrying a jar of water—distinctive since carrying water is usually a woman's task. In the house the man enters, they find a room in an upper story furnished for a meal, large enough for at least thirteen people. To prepare for the Passover, they get a lamb without blemish, unleavened bread, bitter herbs, and wine. As Galileans, they will eat in the evening of 14 Nisan, as the law states (Leviticus 23:5).

Jesus' sacrifice fulfills the requirements of all the Jewish feasts. He fulfills the seven-day Feast of Unleavened Bread by living a sinless life, as leaven is a metaphor for the sin in our lives (Leviticus 23:6). He fulfills the requirement of Firstfruits (Leviticus 23:10) in His resurrection as the "firstfruits of those who have fallen asleep" (1 Corinthians 15:20). After He ascends to heaven, the early church experiences the true Feast of Pentecost, as the Holy Spirit falls on them and causes three thousand to accept Christ as their Savior.

Scholars believe that the fulfilment of the Feast of Trumpets (Leviticus 23:24), Day of Atonement (Leviticus 23:27), and Feast of Booths (Leviticus 23:34) will occur in the future as the rapture of the church (1 Thessalonians 4:13–18), Jesus' second coming (Zechariah 12:10), and the establishment of Jesus' kingship (Micah 4:1–7). But even these are only possible because of the crucifixion and resurrection.

Jesus' death, however, is most closely identified with the Passover. His is our Passover Lamb (1 Corinthians 5:7), who will die as the literal Passover lambs are slaughtered at the temple. The application of His spilt blood will save us from God's holy wrath, even as the blood of the Passover lambs saved the firstborn Israelites from God's vengeance (Exodus 12:1–32). It is not by doing something that we are saved, it is simply by identifying as those who are saved by Jesus' blood.