Then,

his chores being all dispatched, he caught
another brace of men to make his breakfast,
and whisked away his great door slab
to let his sheep go through—but he, behind,
reset the stone as one would cap a quiver.

The use of the epic simile in this excerpt helps readers understand that

the Cyclops has eaten another bunch of Odysseus’s men.
Odysseus and his men are still trapped inside the cave.
the enormous stone is easily and routinely moved by the giant Cyclops.
the Cyclops takes his sheep out to pasture with him in the mornings