1The 24th day of the month (date). Usually read 'nijuu-yokka', though 'nijuu-yon-nichi' may be used in some contexts.
支払いの締め切りは今月の２４日です。
The payment deadline is the 24th of this month.
二十四日のイベントにはたくさんの人が来るだろう。
Many people will likely come to the event on the 24th.
2A period of 24 days (twenty-four days).
実験は合計で２４日続いた。
The experiment lasted a total of 24 days.
商品の返品は受け取りから２４日以内にしてください。
Please return the product within 24 days of receipt.