At Mary’s request, Jesus performs his first miracle.
Marriage and wedding feasts are metaphors used in Scripture to describe God's salvation and the Kingdom of God. Here at the beginning of Jesus' public ministry, John's Gospel seeks to establish that Jesus is going to re-interpret and fulfill Yahweh's promise to Israel. Jesus establishes the New Covenant. A hint about what this New Covenant will be like is made evident in the deed that Jesus performs. Asked to do something to address the awkward situation that the absence of wine at a wedding feast would create, Jesus' miracle produces vast quantities of wine—six jars holding thirty gallons each are filled to overflowing with choice wine.
This lavish response to a simple human need is a vision for us of the abundance of God's kingdom. It challenges us to respond generously when confronted with human need today. We respond as best we can, fully confident that God can transform our efforts, bringing the Kingdom of God to fulfillment among us.
Excerpt, Loyola Press website