Catechism Section 1131
"The sacraments are efficacious signs of grace,
instituted by Christ and
entrusted to the Church, by which divine life is dispensed to us. The visible rites by which the sacraments are celebrated signify and make present
the graces proper to
each sacrament."
Note
that the Catholic Church does not state that the Sacraments are the only way that these graces are bestowed upon us.