What does John 2:13 mean?

Jewish men living in the regions around Jerusalem were expected to attend three yearly festivals in the city (Deuteronomy 16:16). These were Passover, Pentecost, and Tabernacles; also called the Feasts of Unleavened Bread, of Weeks, and of Booths, respectively. The gospel of John also mentions the Feast of Dedication, today called Hanukkah (John 10:22). Some of Jesus' most interesting conversations occurred during these festival times in Jerusalem.

The city was the center of Jewish worship. It was the seat of David's power (2 Samuel 5:6–10) and the location of the temple (1 Kings 6—7). People traveled great distances to offer sacrifices there, and to participate in religious ceremonies. Many of these people owned no livestock. Instead, they had to purchase a suitable sacrifice after they arrived. This led merchants, money-traders, and lenders to set up shop just inside the temple grounds. That could have been a good thing, to help people honor their obligation to God.

Unfortunately, the men there were not focused on telling people about the Lord. Nor were they motivated to help pilgrims. These men were abusing the situation: gouging vulnerable people for the sake of profit.