Here are a couple of things that explains it
@Arc F1
Question:
I’ve always wondered what the Catholic Church means by "blessing," especially in blessing objects. Does the object bear a new and real virtue?
Answer:
Briefly, a blessing on an object is a prayer that praises God for the act of creating this object and implores that the object be used for his greater glory. The
Catechism puts it this way:
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.” This is why the Church imparts blessings by invoking the name of Jesus, usually while making the holy sign of the cross of Christ. (CCC 1671)
Why Do Catholics Bless Stuff?
Catechism
The characteristics of sacramentals
1668 Sacramentals are instituted for the sanctification of certain ministries of the Church, certain states of life, a great variety of circumstances in Christian life, and the use of many things helpful to man. In accordance with bishops’ pastoral decisions, they can also respond to the needs, culture, and special history of the Christian people of a particular region or time. They always include a prayer, often accompanied by a specific sign, such as the laying on of hands, the sign of the cross, or the sprinkling of holy water (which recalls Baptism).
1669 Sacramentals derive from the baptismal priesthood: every baptized person is called to be a “blessing,” and to bless.174 Hence lay people may preside at certain blessings; the more a blessing concerns ecclesial and sacramental life, the more is its administration reserved to the ordained ministry (bishops, priests, or deacons).175
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."176
scborromeo.org/ccc/ccc_toc.htm