What is this part of the Mass?
During the Communion Rite of the Mass, we prepare ourselves to receive the Body and Blood of Christ. The Communion Rite begins with the Lord’s Prayer and continues through the Prayer after Communion. What we do before and while receiving Communion does not change. Together we stand and pray the Our Father. We should not hold hands at this time because our sign of unity comes next. We remember we are one family with God. As a sign of this unity we share a Sign of Peace with those around us. We receive Holy Communion and then we are sent forth. But some of the words will be different in the new translation of the Roman Missal.
 
What do we say now and what is changing?
During the breaking of the bread, the fraction, the priest prays a short prayer as he places a small piece of the consecrated host into the chalice. While he does that we say or sing the Agnus Dei (AHG-noos DAY-ee), the Lamb of God. Lamb of God is a name for Jesus that reminds us Jesus died for our sins. There are no changes to the Lamb of God.
Just before we go to receive Holy Communion, the priest makes a proclamation and then joins us in the response. Both parts of this dialogue will have some changes:

Priest: “Behold the Lamb of God, behold him who takes away the sins of the world. Blessed are those called to the supper of the Lamb.”
All: “Lord, I am not worthy that you should enter under my roof, but only say the word and my soul shall be healed.”

Instead of saying “this is the Lamb of God” the priest will say “Behold the Lamb of God”. This is closer to the Latin, Ecce Agnus Dei (EH-chay AHG-noos DAY-ee), more majestic in sound, and a direct reference to John 1:29 where John the Baptist points out Jesus to his followers. The word “happy” has been changed to “blessed.” You may be blessed even when you aren’t feeling so happy. This together with the direct reference to “the supper of the Lamb” makes clear the connection to Revelation 19:9. There, the angel in the vision has John write down the words that proclaim ‘blessed are all those called to the wedding feast of the Lamb.’ Our response, “Lord, I am not worthy that you should enter under my roof, but only say the word, and my soul shall be healed,” echoes the words of the Centurion, who asked Jesus to heal his servant in Luke 7:6-7 and Matthew 8:5-13. As we are presented with the very Body and Blood of Christ, we are called to the same, deep level of faith as the Centurion.

Return reverence to the Mass:  While the priest receives communion following the Agnus Dei, we should each bow our heads and silently make an Act of Faith:
"Lord, I am about to receive you in the Eucharist; body, blood, soul, and divinity.
I believe thus Truth because you have taught it. You who can neither deceive nor be deceived. I am willing to die for this Truth."