# A certain silversmith named Demetrius

The use of the words "a certain" introduces a new person in the story. 

# silversmith

a craftsman who works with silver metal to make statues and jewelry

# named Demetrius

This is the name of a man. Demetrius was a silversmith in Ephesus who was against Paul and the local church.

# brought in much business for the craftsmen

"enabled those who made the idols to make much money"

# shrines of Artemis

These were probably carved or molten images of the temple of Artemis or of the part of the temple in which the statue of Artemis stood.