The Glossary of the Catechism of the Catholic Church (“CCC”)
defines the term “communion”.
After speaking of the bread and wine, it goes on to say:
“More generally, our fellowship and union with Jesus
and other baptized Christians in the Church, …”
Let’s breakdown those two aspects of being in communion.
FELLOWSHIP
God wants fellowship with you; that is friendship, companionship, love.
You are a unique individual and God treasures your individuality.
UNION
At the same time God wants to be in union with you.
God freely gives Himself to you.
He hopes and dreams that you will freely give yourself to Him.
God hopes for:
unity in commitment;
unity in understanding;
unity in love.
So you see, communion is a free, voluntary commitment to each other
and simultaneously an enjoyment of each other’s uniqueness.
I consider it another way to talk about sharing a mutual love.
Our communion with Jesus / our mutual love with Jesus is central to the purpose of our lives.
We Roman Catholics often use the term “communion” to refer to receiving
the body and blood of Christ in the form of bread and wine.
This is just a shorthand way of saying that we
are celebrating and renewing our communion with Jesus.
Jesus left you a letter expressing His love of you.
Read it and increase your communion with Him: Jesus love letter
You can find some of the official teachings of the Roman Catholic Church on Communion here