A quick description of the sacraments:

1. They are holy signs and seals of the covenant of grace.
2. They are instituted by God.
3. They represent Christ and his benefits.
4. They confirm our interest in Christ, and differentiate between the visible Church and the world.
5. They solemnly engage members of the Church to God's service, according to his Word.

God has given us two sacraments:

          Baptism, and the Lord's Supper.

Here is a more detailed definition of the sacraments, in the WCF.