ˁēz clearly denotes a single she-goat in the singular (cf. the symmetrical opposition ˁizzīm ~ tǝyāšīm vs. rǝḥēlīm ~ ˀēlīm in Gn 32.14), but may have a collective meaning without gender distinction in the plural.
Hebrew
ˁzb - to leave, abandon; to leave behind; to let go
(HALOT 806)