atha — thereafter; kadācit — at some time; kaścit — some; vṛṣala-patiḥ — the leader of śūdras engaged in plundering the property of others; bhadra-kālyai — unto the goddess known as Bhadra Kālī; puruṣa-paśum — an animal in the shape of a man; ālabhata — started to sacrifice; apatya-kāmaḥ — desiring a son.
At this time, being desirous of obtaining a son, a leader of dacoits who came from a śūdra family wanted to worship the goddess Bhadra Kālī by offering her in sacrifice a dull man, who is considered no better than an animal.
Low-class men such as śūdras worship demigods like Goddess Kālī, or Bhadra Kālī, for the fulfillment of material desires. To this end, they sometimes kill a human being before the deity. They generally choose a person who is not very intelligent — in other words, an animal in the shape of a man.