Comentario citado sobre Levítico 12:6

ויהי מקץ שנתים ימים, two whole years according to Leviticus 25,29-30 ימים תהיה גאולתו, “it may be redeemed until the end of one year.” Here the Torah speaks of שנתים, i.e. twice a year. The word ימים as meaning a year has already occurred in Genesis 24,54 ימים או עשור, “a year or at least 10 months.” Also in Exodus 13,10 we find the expressionמימים ימימה, which means: “from year to year, annually.” When the words מקץ שנתים occur without the addition of the word ימים, they mean “one year.” When an animal did not yet reach the first anniversary of its birth it is called as being בן שנתו, “an up to one year old.” (compare Leviticus 12,6)

Kinim is the plural of the word "ken" and it refers here to a pair of birds brought as a sacrifice (in Biblical and modern Hebrew, ken is a nest). There are several cases in the Torah where a person has to bring a pair of birds, either turtledoves or pigeons, one as an olah and one as a hatat. For instance, concerning the zav (man with abnormal genital discharge), Leviticus 15:14-15 states, "On the eighth day he shall take two turtledoves or two pigeons….The priest shall offer them, the one as a sin offering and the other as a burnt offering." The zavah brings the same offerings (ibid 29-30). A woman also brings these offerings after childbirth (Leviticus 12:6-8), if she is not wealthy enough to bring a ram. A nazirite who was made impure brings them on the eighth day of his purity ritual (Numbers 6:10-11). There are other such cases as well (see Leviticus 5:1-10). A person can also voluntarily bring bird sacrifices (see Leviticus 1:14-17). In this case the bird is a sacrificed as an olah (burnt offering) and not a hatat.

Introduction According to Leviticus 12:6, after a woman gives birth and then undergoes a period of purification, she must bring two offerings. The first is a lamb, offered as an olah, and the second is a bird for a hatat. The remainder of our chapter deals with various scenarios in which a woman would bring a hatat and either eat it or not.

בכל קדש [SHE SHALL NOT TOUCH] ANYTHING THAT IS HOLY — not anything: this serves to include the heave-offering (Makkot 14b; Yevamot 75a). The Torah prescribes this because such a woman must be regarded as one who has taken the immersion on a very long day (טבולת יום ארוך), because she immersed herself at the end of the first seven days whilst her sun does not set to bring about her purification until sunset of the fortieth day since it is only on the morrow that she has to bring the atonement offering in connection with her purification, as it is stated in v. 6.