A figure of speech is any use of language that goes beyond the literal meaning of words. It can include effects for emphasis, such as repetition or rhyme.
Line 10 uses more than one figure of speech:
The moping owl does to the moon complain . . .
First, it employs alliteration, an effect that puts words that begin with the same consonant in close proximity. This creates a sense of rhythm and emphasis. In the line above, "moping" and "moon" both begin with m, which puts emphasis on those two words.
Second, line 10 personifies the owl. Personification is attributing human characteristics to an animal or object. The owl is described as "moping" and "complaining," characteristics typical of humans, not animals.
Lines 18–19 also use alliteration in the repetition of s and c sounds at the beginnings of words:
The swallow twitt'ring from the straw-built shed,
The cock's shrill clarion, or the echoing horn . . .
Line 20 employs euphemism
, which is a polite or roundabout way of saying something harsher:
No more shall rouse them from their lowly bed.
This line means that the swallow, cock, and horn will no longer rouse the people in the country churchyard because they are dead and buried. "Lowly bed" is a euphemism for a grave.