en_tn/num/28/17.md

the first month, on the fourteenth day of the month ... On the fifteenth day of this month

"During the first month, on day 14 of the month ... On day 15 day of this month." This refers to the first month of the Hebrew calendar. (See: rc://en/ta/man/translate/translate-hebrewmonths and rc://en/ta/man/translate/translate-ordinal)

a feast is to be held

This can be stated in active form. "you must have a feast" (See: rc://en/ta/man/translate/figs-activepassive)

bread without yeast must be eaten

This can be stated in active form. "you must eat bread without yeast" (See: rc://en/ta/man/translate/figs-activepassive)