In kaʾannahu ḥabbu fulful, kaʾanna introduces a comparison: “as though it were peppercorns.” The dark, small, rounded pellets are likened to pepper seeds in observable shape and appearance.
The pronoun -hu refers back to baʿar, a collective noun, so a singular pronoun is appropriate. Ḥabbu fulful is a construct phrase functioning as the predicate of the comparison.
This simile is not an ornament detached from meaning. Its fine visual detail makes the deserted site vivid and emphasizes the silence left by its former inhabitants.