"Quarter hour" is the Engpsh equivalent for "一刻钟".
The phrase comes from the fact that a quarter hour is one-fourth of an hour, the traditional time measurement unit.
Example sentence:
"I'll be back in a quarter hour." (我一刻钟后回来)
Another way to say this is "15 minutes"
Example sentence:
"Can you give me 15 minutes? " (可以给我15分钟吗？)