There are two parts to what a Sacrament is as we see in the "Outline of Faith". The first past is that a Sacrament is an "outward and visible sign of inward and spiritual grace." A great example of what this means comes from the Two Great Sacraments: Holy Baptism and Holy Eucharist. In Baptism, the water and the threefold name of the Trinity are outwards signs of the spiritual grace of being united to Jesus' death and Resurrection as we are born anew into new life with our Lord. In the Eucharist, the bread and the wine are outward signs of the Body and Blood of Christ Jesus.
Sacraments are also "given by Christ as sure and certain means by which we receive that grace." In Baptism and Eucharist, we are given signs that we are united in Christ Jesus. As Paul reminds us in Romans:
If we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his.
Our union with Jesus is a sure sign that we too will live into the Resurrection, God's ultimate gift of Grace and our hope for this life and the next.