Which sin is the Pasuk discussing?
Rashi: It is discussing a Yachid who transgresses Avodah-Zarah (in a way that is Chayav Kareis be'Meizid and a Chiyuv Chatas be'Shogeg - Horayos, 8a). 1
Sifsei Chachamim: Which we learn from the 'Vav' of "ve'Im" which connects this Parshah wih the previous one concerning a Tzibur.
Who is Nefesh Achas referring to?
Rashi (in Kerisos, 26a): It refers to a Yachid, irrespective of whether he is a layman, the king or a Kohen Gadol. 1
As implied by ?Nefesh Achas?, which incorporates a Yahid, a Nasi and a Kohen Gadol (Horayos, 7b).
In what way is this Chatas different than a regular Chatas?
Rashi: In that the sinner is obligated to bring a female kid-goat exclusively, whereas by a regular Chatas, he has the option of bringing a Kisbah (a female lamb).
Why does the Torah not give someone who sinned ba?Avodah Zarah the option to bring a Kisbah?
Oznayim la'Torah (based on Sotah, 32b): It is based on the fact that the Torah did not differentiate between the location of a Chatas and that of an Olah, so that people would not know whether the sinner is bringing an Olah as a gift or a Chatas as a sin-offering, thereby sparing the sinner the embarrassment of being recognized - because, even though an Olah is a male and a Chatas, a female, since the Kisbah has a fat-tail which covers its Makom Ervah, people will not know whether it is a male or a female lamb. However, when it comes to Avodah Zarah, where the person needs the extra embarrassment as part atonement for his grave sin, the Torah insists that he brings a Se'irah, which everone knows can only be a Chatas to enble the sinner to attain complete forgiveness for his sin. 1
See Oznayim la'Torah.
Why does the Torah write "Nefesh" with regard to a Chatas?
Refer to Vayikra 4:2:1:1-4.
