What are the connotations of the words "b'Etzem ha'Yom ha'Zeh"?
Ramban, Moshav Zekenim: It says so about Chadash, Shavu'os, Yom Kipur, but not the other Yamim Tovim. Literally it means 'on this very day.' 1 Even though the Torah discusses at length the Omer, Shtei ha'Lechem and the accompanying Korbanos, the Kedushah and Isur Melachah of Shavu'os do not depend on them. Likewise, the Inuy, Isur Melachah and Kaparah of Yom Kipur do not depend on the Korbanos 2 , and Chadash is forbidden before the day [of the Omer] and permitted after it, even if the Omer is not brought. All these matters depend on the day itself. 3
Ramban #3 (citing the Toras Kohanim): When the Pasuk uses the term "b'Etzem ha'Yom ha'Zeh" in connection with the Yamim-Tovim, it means on this very day - from nightfall to nightfall, to preclude the Tosefes from Kares (by Yom Kipur) and from the Kedushah of Yom-Tov by Shavu'os. 7
Ramban: As emerges from the opening Parshah of Acharei-Mos.
Ramban: We also find this expression on other occasions, where the Pasuk is coming to stress on this day and not on another one - See Bereishis 7:13, 17:26, Shemos 12:41 and Devarim 32:48 (and Ramban there).
Ramban: As if it would have written "b'Otzem ha'Yom ha'Zeh".
Ramban: According to this explanation, we can explain all the other places where the Torah uses the same term in the same way (See Ramban).