"in the 1st month." This is the first month of the Hebrew calendar. It marks when God brought the people of Israel out of Egypt. (See: [[rc://en/ta/man/translate/translate-hebrewmonths]] and [[rc://en/ta/man/translate/translate-ordinal]])
Here "they" refers to the people of Israel. The phrase "came out" means to leave. AT: "after they left the land of Egypt" (See: [[rc://en/ta/man/translate/figs-idiom]])
# Let the people ... at its fixed time of year
The word "fixed" means "previously set." This means that this is when the observe it every year. AT: "Let the people ... at the time of year they currently observe it" (See: [[rc://en/ta/man/translate/figs-explicit]])
# On the fourteenth day ... at its fixed time of year
This is the set time of year that they celebrate the Passover. The full meaning of this statement can be made clear. AT: "On the fourteenth day ... and observe it, for this is the time you do celebrate it every year" (See: [[rc://en/ta/man/translate/figs-explicit]])
# the fourteenth day
"the 14th day" (See: [[rc://en/ta/man/translate/translate-ordinal]])
# follow all the regulations, and obey all the decrees
These two phrases mean basically the same thing and are combined to emphasize that they needed to obey the commands. (See: [[rc://en/ta/man/translate/figs-parallelism]])
Here the phrase "keep it" is an idiom which means to observe it. AT: "You must observe it" or "You must celebrate it" (See: [[rc://en/ta/man/translate/figs-idiom]])