Catholics believe the Eucharist, or Communion, is both a sacrifice and a meal. We believe in the real presence of Jesus, who died for our sins. As we receive Christ's Body and Blood, we also are nourished spiritually and brought closer to God.
Holy Communion: Our Life in Christ

The Sacrament of Holy Communion is the third of the Sacraments of Initiation. Even though we are required to receive Communion at least once per year (our Easter Duty), and the Church urges us to receive Communion frequently (even daily, if possible), it is called a sacrament of initiation because,  like Baptism and Confirmation, it brings us into the fullness of our life in Christ.

I am the living bread which came down from heaven.  If any man eat of this bread, he shall live for ever; and the bread that I will give, is my flesh, for the life of the world.  The Jews therefore strove among themselves, saying: How can this man give us his flesh to eat? Then Jesus said to them: Amen, amen I say unto you: Except you eat the flesh of the Son of man, and drink his blood, you shall not have life in you.  He that eat my flesh, and drink my blood, will have everlasting life: and I will raise him up in the last day. (John 6:51-55)