The Korean reading for "second" (of which there are 60 in a minute) is 초.
Is this a native word unrelated to 秒, or is it somehow a reading of 秒? The expected reading would be 묘 and I don't know of any reflexes of 초 in Chinese or Japanese with the meaning of "second".
Most of the Korean Hanja readings are directly related to the Middle Chinese pronunciations/Qieyun rimes. But this one is a classical example of a 와음 현상.
秒 should be "묘" by principle, but people misread the character, misrecognizing it as 抄 or 炒, which both have the reading "초", and they did it so much that it stuck and became the standard. Other characters like this are 歐 which should be 우, but read as 구, influenced by 區, and 粘 which should be 념 but is 점 influenced by 占.
