The intercession of the saints refers to the ongoing prayer and advocacy of those who are in Heaven for the Pilgrim Church on earth. Because all the faithful are united in the one Body of Christ, death does not sever the bonds of charity or prayer (CCC 956).
Alive in Christ
The saints in Heaven are not dead but fully alive in Christ. Because they are perfectly united to God, their intercession is powerful and unceasing. They do not replace Christ's unique mediation, but participate in it, presenting our needs to the Father through the Son (CCC 956, 2683).
The Communion of Saints
This practice is a direct expression of the Communion of Saints. Just as Christians on earth ask for each other's prayers, the Church has always asked the saints in Heaven to pray for her members. Their intercession is their most exalted service to God's plan (CCC 956).
May the Lord bless you and keep you.