John Gill 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 which he has sinned come to his knowledge ,
&c.] So that he is convinced that he has sinned:

then he shall bring his offering ;
to the door of the tabernacle of the congregation, to the priest there:

a kid of the goats :
a young goat:

a female without blemish ;
and so inferior to the offering of the ruler or prince; for the characters of men are aggravations of their sins, and sacrifices were to be in some measure answerable to them, and suitable to their circumstances:

for the sin which he has sinned ;
to atone for it in a typical way.