Albert Barnes Commentary Isaiah 41:16

"Thou shalt winnow them, and the wind shall carry them away, and the whirlwind shall scatter them; and thou shalt rejoice in Jehovah, thou shalt glory in the Holy One of Israel." — Isaiah 41:16 (ASV)

You shall fan them - Keeping up the figure begun in the previous verse. To fan here means to winnow, an operation that was performed by throwing the threshed grain up with a shovel into the air, so that the wind drove the chaff away. So all their enemies, and all the obstacles that were in their way, would be scattered.

And the whirlwind shall scatter them - The ancients believed that people might be swept away by a storm or whirlwind. See Job 27:0:

The cast wind carries him away and he departs;
And as a storm hurls him out of his place.

Compare Homer, Odyssey 20:63 and following, thus rendered by Pope:

Snatch me, you whirlwinds! far from human race,
Tossed through the void limitless space;
Or if dismounted from the rapid cloud,
Let ocean shroud me with his whelming wave!

See the notes at Job 30:22.

And you shall rejoice in the Lord - In view of the aid which He has granted, and the deliverance which He has performed for you.

You shall glory - You shall boast, or you shall exult. You will regard God as the author of your deliverance, and joy in the proofs of His interposition, and of His gracious protection and care.