The answer
The censer is a vessel made of copper or silver in the shape of a cup, in which incense is burned. In the usual form of the censer, the container is suspended from three chains from which it can be swung. The censer symbolizes St. Mary who bore the “true live coal,” that is the incarnate Son of God. Its three chains remind us of the Holy Trinity who participated in the incarnation of the Son, for the Father sent His Son, the Son obeyed, and the Holy Spirit came upon the virgin for the incarnation of the Son.
Fr. Tadros Yacoub Malaty