"The whole liturgical life of the Church revolves around the Eucharistic sacrifice and the sacraments" (Catechism of the Catholic Church, 1113).
The seven sacraments are ceremonies that point to what is sacred, significant, and important for Christians. They are also special occasions for experiencing God's saving presence. That's what theologians mean when they say that sacraments are both signs and instruments of God's grace. The sacraments nourish and strengthen us as they express and build up our faith.