Rashi on Leviticus 12:4/רש"י על ויקרא י״ב:ד׳

1תשב — The word תשב signifies here “remaining”, just as in (Deuteronomy 1:46) “And ye stayed (ותשבו) at Kadesh”, and (Genesis 13:18) “and he stayed (‎‎‎וישב) in the Plain of Mamre”

2 בדמי טהרה IN THE BLOOD OF PURIFICATION — Even though she see an issue of blood she is nevertheless clean (Sifra, Tazria Parashat Yoledet, Chapter 1 7).

3בדמי טהרה — There is no Mappik in the last 'ה‎ of טהרה (as there is in the last word of this verse): it (the word) is an uninflected noun similar in meaning to טֹהַר (being a feminine form of it).

4ימי טהרה — the 'ה here has a Mappik and the meaning is: the days of her טֹהַר, her purification.

5בכל 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.

6לא תגע SHE SHALL NOT TOUCH — This is a prohibition addressed to anyone who would eat holy things in a state of uncleanness, as it is stated in a Baraitha in Yevamot 75a.