14th day of the month
Used to specify the 14th day in dates. The reading じゅうよっか is irregular; note the small っ.
The meeting will be held on the 14th.
Please submit it by the 14th of next month.
14 days; two weeks
Used for a duration of 14 days. Often interchangeable with 二週間, but 十四日 can emphasize the exact number of days.
Please continue taking this medicine for 14 days.
He was discharged from the hospital 14 days after the surgery.
The meeting will be held on May 14th.