What does the Catholic Church mean by the Real Presence?

The Real Presence is the Catholic doctrine that Jesus Christ is truly, really, and substantially present — Body, Blood, Soul, and Divinity — in the Eucharist under the appearances of bread and wine after the Consecration at Mass. This is not merely a symbolic or spiritual presence but the actual, complete presence of the risen Christ. The change is called transubstantiation: the substance (inner reality) of the bread and wine is wholly changed into the substance of Christ's Body and Blood, while the accidents (appearances — taste, texture, color) of bread and wine remain. This doctrine is grounded in Jesus' own words: 'This is my body' (Luke 22:19) and the Bread of Life Discourse in John 6:51-56: 'Unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you.' The Church Fathers unanimously affirmed the Real Presence from the earliest centuries — St. Ignatius of Antioch (c. 110 AD) condemned those who 'abstain from the Eucharist because they do not confess that the Eucharist is the flesh of our Savior Jesus Christ.' The Real Presence endures as long as the Eucharistic species remain, which is why the Blessed Sacrament is reserved in the tabernacle and venerated in Adoration.