Kairos and Chronos
The ancient Greeks had two words for time, and kairos was the second. The first was Chronos, which we still use in words like chronological and anachronism. It refers to clock time — time that can be measured — seconds, minutes, hours, years.

Where Chronos is quantitative, kairos is qualitative. It measures moments, not seconds.
Further, it refers to the right moment, the opportune moment. The perfect moment. 

In the Bible, Kairos means the “right time,” “opportune season,” or “appointed moment” when God acts,
contrasting with Chronos (ordinary, sequential time). 
It signifies a critical, God-ordained time for a divine purpose, such as salvation, revelation, or fulfilling prophecy, requiring a responsive decision from people, like Jesus’ proclamation:

The kairos is fulfilled, the kingdom of God is at hand! (Mark 1:15).