He counted the days on the calendar.
Meaning: This means that he was eagerly looking forward to his birthday party and was marking off the days on the calendar to see how much longer he had to wait.
Choice of Words: Counted means to determine the number of something by adding them one by one. Days are periods of 24 hours. Calendar is a system of organizing days, weeks, and months. When you put them together, it means he was keeping track of the days remaining until his birthday party by marking them off on a calendar.
Alternative Expressions
Related Expressions