This is the 24th most frequent Arabic word.
يوم
Day.
In this sentence, 'يوم' is used as a noun referring to a specific day of the week, 'Sunday'.
يوم الأحد هو بداية الأسبوع.
Sunday is the beginning of the week.
In this sentence, 'يومًا بعد يوم' expresses repetition of an action over consecutive days, exemplifying its role in an idiomatic expression.
للنجاح يجب أن تعمل يومًا بعد يوم.
To succeed, you have to work day after day.
Here, 'يومًا' is used to indicate a day experienced or spent, showcasing its use in the accusative case to describe the time context.