What does John 2:3 mean?

Being a good host was extremely important in the ancient Middle East. Weddings were important social events; guests came from far away. It was critical for the bride and groom to make a good impression. Wedding guests expected there to be enough food and drink to last the entire, several-day celebration. Fair or not, just as today, local custom put tremendous pressure on newlyweds to entertain their guests. Since Jesus' friends and family were poor, it's not surprising that they ran out of wine. This would not have made it any less embarrassing for the couple.

It's important to note that Mary doesn't make any demands of Jesus. She does not ask Him to do anything specific. As far as John records it, she doesn't "ask" anything, at all. She simply brings the need to Him. This is consistent with the rest of the four gospels: at no time does Mary approach Jesus with any type of request. The Bible doesn't support the idea that Mary is specially empowered to speak to Jesus on behalf of others. As it happens, when she first approaches Him, Jesus comments that He's not directly involved in what's happened so far (John 2:4).

Also of note is that Jesus had never performed a miracle at this point in His life (John 2:11). Non-biblical texts have added fantastic tricks and displays of power to Jesus' childhood, but none are from legitimate sources. Mary's trust in Jesus is that much more impressive, knowing that she had never seen Him perform a miracle. All she knew is that He could solve the problem.