Meanings Taken from Catholic Catechism:
Chi Rho (symbol for Christ):1391 Holy Communion augments our union with Christ. the principal fruit of receiving the Eucharist in Holy Communion is an intimate union with Christ Jesus. Indeed, the Lord said: "He who eats my flesh and drinks my blood abides in me, and I in him."Life in Christ has its foundation in the Eucharistic banquet: "As the living Father sent me, and I live because of the Father, so he who eats me will live because of me." (par. 1391)

Crosses on Calvary: “The Eucharist is a sacrifice because it makes present the sacrifice on of the cross” (par. 1366)

Lamb: Jesus is the Lamb of God who takes away the sins of the world.
Chalice and Host: The sacrament of the Eucharist is above all other sacraments because, “in the most blessed sacrament of the Eucharist the body and blood, together with the soul and divinity of our Lord Jesus Christ, and therefore, the whole Christ is truly, really and substantially contained.” (par 1374)

Wheat and Grapes: The Eucharist is a thanksgiving and praise to the Father because, “we offer to the father what he has himself given us: the gifts of his creation, bread and wine which...become the body and blood of Christ, (par.1357).

Dove (Holy Spirit): Communion with the flesh of the risen Christ, a flesh “given life and giving life through he Holy Spirit, preserves, increases, and renews the life of grace received at Baptism, (par. 1392).

Christ, Tree of Life:  Every time this mystery is celebrated, "the work of our redemption is carried on" and we "break the one bread that provides the medicine of immortality, the antidote for death, and the food that makes us live for ever in Jesus Christ." (par. 1405)

Jerusalem Cross: The sacrifice of Christ and the sacrifice of the Eucharist are one single sacrifice: "The victim is one and the same: the same now offers through the ministry of priests, who then offered himself on the cross; only the manner of offering is different." "In this divine sacrifice which is celebrated in the Mass, the same Christ who offered himself once in a bloody manner on the altar of the cross is contained and is offered in an unbloody manner." (PAR. 1367)

Monstrance: (Par 1418) Because Christ himself is present in the sacrament of the altar, he is to be honored with the worship of adoration. "To visit the Blessed Sacrament is . . . a proof of gratitude, an expression of love, and a duty of adoration toward Christ our Lord" (Paul VI, MF 66)

Other symbols:
Candle: The tabernacle candle is kept alight to indicate and honor the presence of Christ.

Mary bead (M with crown of stars): Mary, the Mother of God, leads us to Jesus.

Trinity Knot Bead: Through the work of the Holy Spirit, Jesus becomes present on the alter to sacrifice himself to the Father for the forgiveness of sins.

“Unless we have Jesus, we cannot give Him. That is why we need the Eucharist.”   -Mother Teresa