This is the 12792nd most frequent Russian word.
круглосуточная
24-hour or round-the-clock.
Here, 'круглосуточную' is used as an adjective modifying 'pharmacy', emphasizing that it operates around the clock.
Я нашёл круглосуточную аптеку.
I found a 24-hour pharmacy.
In this sentence, 'Круглосуточная' is a nominalized adjective meaning 'working all day and night', describing the general concept of continuous work.
Круглосуточная работа выматывает.
Working around the clock is exhausting.
Here, 'круглосуточным' serves as an adjective describing the status of the store, denoting it started operating all day and night.