Charles Ellicott Commentary Leviticus 4:28

"if his sin, which he hath sinned, be made known to him, then he shall bring for his oblation a goat, a female without blemish, for his sin which he hath sinned." — Leviticus 4:28 (ASV)

Or if his sin ... come to his knowledge. —That is, is shown to him by another person. (See Leviticus 4:23.)

A kid of the goats. —Better, a shaggy-haired she-goat without blemish. The expression is feminine in the Hebrew. The female was of less value than the male, and was therefore more suitable to the circumstances of the ordinary people.