This is the first month of the Hebrew calendar. It marks when God brought the people of Israel out of Egypt. It is during the last part of March and the first part April on Western calendars. (See: [[rc://en/ta/man/translate/translate-hebrewmonths]] and [[rc://en/ta/man/translate/translate-names]])
It is implied by "keep the Passover" that they would celebrate and eat the Passover meal. Alternate translation: "celebrate the Passover meal" or "eat the Passover meal" (See: [[rc://en/ta/man/translate/figs-explicit]])