Every Catholic Church has a special gold box in the sanctuary. Near this gold box will be a red candle, sometimes hanging from the ceiling.
The purpose of the Tabernacle is to store the Eucharist when mass is not being said, and purpose of the Tabernacle Lamp is to remind us that God is with us… Emmanuel (Matthew 1:23). Rarely, the Lamp will be out, because the Eucharist will not be inside the Tabernacle. This happens on Good Friday, for example.
Jesus is present there, in the Eucharist, he is the bread that came down from heaven… his body, blood, soul and divinity is present there. Yes, Emmanuel, God with us, present tense. Discerning his body is part of our calling as Christians (1 Cor. 11:29).
My eldest daughter is looking for a church. Naturally, I want her to be a Catholic but I also know that it takes time… she was raised in a gnostic cult, after all. I mentioned that she could always go to the Catholic Church, and encouraged her by saying, “Jesus is there, waiting for you.” Because it’s true. He is.