# The courtyard gate must be a screen twenty cubits long

"You must make a screen twenty cubits long to be the courtyard gate"

# The curtain must be made ... fine twined linen, the work of an embroiderer

"They must make the curtain ... fine twined linen, the work of an embroiderer" 

# blue, purple, and scarlet material and fine twined linen

"yarn that is dyed blue, purple, and scarlet," probably wool yarn, or "blue, purple, and scarlet dye" to dye the linen.

# an embroiderer

a person who sews designs into cloth