As he was returning with the hind, Heracles encountered Artemis and her twin, Apollo, and begged the goddess for forgiveness, explaining that he had to catch it as part of his penance, but he promised to return it.
Heracles encountered Artemis. Heracles encountered her twin. Heracles begged the goddess for forgiveness. He had to catch it as part of his penance. This was what heracles were explaining. He was returning with the hind. Her twin was Apollo. He promised to return it.