Catechism of the Catholic Church 1097
In the liturgy of the New Covenant every liturgical action, especially the celebration of the Eucharist and the sacraments, is an encounter between Christ and the Church. The liturgical assembly derives its unity from the "communion of the Holy Spirit" who gathers the children of God into the one Body of Christ. This assembly transcends racial, cultural, social - indeed, all human affinities.
Sacrosanctum Concilium (Constitution on the Sacred Liturgy) #59
The purpose of the sacraments is to sanctify men, to build up the body of Christ, and, finally, to give worship to God; because they are signs they also instruct. They not only presuppose faith, but by words and objects they also nourish, strengthen, and express it; that is why they are called "sacraments of faith." They do indeed impart grace, but, in addition, the very act of celebrating them most effectively disposes the faithful to receive this grace in a fruitful manner, to worship God duly, and to practice charity. It is therefore of the highest importance that the faithful should easily understand the sacramental signs, and should frequent with great eagerness those sacraments which were instituted to nourish the Christian life.
Additional Resources on the Sacraments and the Liturgy:
Catechism of the Catholic Church
Searchable Catechism of the Catholic Church
USCCB Committee on Divine Worship
Vatican II Constitution on the Sacred Liturgy (Sacrosanctum Concilium)