This Shabbat is a double Parsha of ויקהל-פקודי and פרשת החודש. We finish the book of שמות and we "bench" Rosh Chodesh for the month of Nissan on Tuesday.
The idea in Parshat החודש is that the Jewish calendar begins with the month of Nissan that is to be viewed as the first month. We began as a nation in Egypt which makes sense that we begin with Nissan.
Another idea that is learned is that certain laws were given in Egypt even though it was a place of great impurity. The של״ה הקודש describes these Mitzvot as an engagement gift between Hashem and the Jewish people. The real gift, that is, the entire Torah, was given on Mount Sinai when we went from being engaged to being married to Hashem.
The third idea in פרשת החודש is that Moshe Rabbeinu was shown how to count the new month based on the new moon. On a mystical level, Eisav is compared to the sun, and Yakov, the moon. As long as Eisav's light shines, Yakov's light is not fully noticed.
Thank G-d we are living in a time where Eisav's light is weakening and Yakov's light is shining brighter and brighter. Shabbat Shalom