A few lines from the Catechism:
They signify effects, particularly of a spiritual nature, which are obtained through the intercession of the Church. By them men are disposed to receive the chief effect of the sacraments, and various occasions in life are rendered holy.
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1670 Sacramentals do not confer the grace of the Holy Spirit in the way that the sacraments do, but by the Church’s prayer, they prepare us to receive grace and dispose us to cooperate with it. “For well-disposed members of the faithful, the liturgy of the sacraments and sacramentals sanctifies almost every event of their lives with the divine grace which flows from the Paschal mystery of the Passion, Death, and Resurrection of Christ. From this source all sacraments and sacramentals draw their power. There is scarcely any proper use of material things which cannot be thus directed toward the sanctification of men and the praise of God.”
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1671 Among sacramentals blessings (of persons, meals, objects, and places) come first. Every blessing praises God and prays for his gifts. In Christ, Christians are blessed by God the Father "with every spiritual blessing."177 This is why the Church imparts blessings by invoking the name of Jesus, usually while making the holy sign of the cross of Christ.
1674 Besides sacramental liturgy and sacramentals, catechesis must take into account the forms of piety and popular devotions among the faithful. The religious sense of the Christian people has always found expression in various forms of piety surrounding the Church’s sacramental life, such as the veneration of relics, visits to sanctuaries, pilgrimages, processions, the stations of the cross, religious dances, the rosary, medals,180 etc.
scborromeo.org/ccc/ccc_toc.htm