The Tabernacle is a wooden box in which the Eucharistic elements, having been consecrated, are reserved, not only for giving to the sick, but for the Eucharistic presence of Christ to abide in His Church. Tabernacle simply means "dwelling place," and what we mean by it is that, just as God dwelt among His people in the Old Testament in the Tabernacle as they journeyed through the desert, and in the Temple Holy Place on Mount Zion, so God in Christ is dwelling among His people wherever they worship him.
G.K. Chesterton was once asked how Jesus would respond to the problems of the world if he were on earth today. He responded "Christ is on earth today; alive on a thousand altars;"
As we head into Ascensiontide, we are reminded of the truth that, though the visible presence of Christ in human form is gone from us, what he says is true: "I am with you always, to the end of the age." (Matthew 28:20)
This ongoing presence is made evident by the lighting of a candle in a visible place near the Tabernacle, which we refer to as a Sanctuary Lamp, which is evocative of the lamps in the Holy Place of the Temple, now marking the most holy place within the church. The Lamp tells everyone who enters, Christ is present here! You have come to worship him! And when you leave - you bring that presence of Christ with you into the world.
Many people find themselves drawn to visit and adore Christ in the Eucharist. That is something I want to encourage you to do, and I'm happy to open up the church to anyone who desires it.