This year, Jews in Israel are celebrating Pessach (Passover) from the evening of 6 April until the evening of 13 April 2012. Jews living in the Diaspora traditionally keep an additional day. Pessach is a biblical holiday for Jews and stands for the Exodus from Egypt. For seven days, we are not allowed to eat any grains like rye, wheat, spelt, barley or oats. In addition to that we also have to avoid products made of these grains such as beer, noodles, pizza, flour, soup powder (without the "kasher le'Pessach" label) etc.
The translation for PESSACH is PASS OVER.
The actual meaning of the word comes from the night when G - d took the lives of the Egyptian firstborn and showed mercy towards the Jews. The Tenth Plague, the death of the firstborn, caused Paraoh to change his mind and let the Jewish people go. Before the night started, G - d commanded the Jews to slaughter a lamb or kid and place the animal's blood on the doorposts. Thus, the Angel of Death would pass over the Jewish home and not take the life of the Jewish firstborn. (see Exodus – Sefer Shemot 12:3 – 7).
The Shabbat preceding Pessach is called SHABBAT HA’GADOL (the Great Shabbat). Why is the Shabbat called by this name ?
This year, according to the Jewish calendar, the Shabbat Ha'Gadol is going to be the 8th Nissan (Chet Nissan). In the year when the Israelites were leaving Egypt, the Shabbat Ha'Gadol was the 10th Nissan (Yud Nissan). According to the Torah, the 10th Nissan was the night when G - d carried out the 10th Plague and let the miracle happen that the Jewish firstborn survived. See about the date Exodus 12:3 as well as the Mishna Berura - Hilchot Pessach, Siman תל תלא.
This upcoming Shabbat we are celebrating SCHABBAT HA'GADOL !