# they will become like stubble. The fire will burn them up

Yahweh compares the magicians and sorcerers to straw that burns quickly in a fire. This means that Yahweh will destroy them as easily as fire burns stubble, and so they are powerless to save Babylon.

# the hand of the flame

"the power of the flame" 

# There are no coals to warm them and no fire for them to sit by

Yahweh emphasizes that this is a destructive fire by stating that it is not one that people will use to warm themselves.