This is the 188th most frequent Chinese word.
快
"Fast," "quick," or "happy."
In this sentence, '快' is used to mean 'almost' or 'soon', indicating an imminent action.
我快要到家了。
I am about to arrive home.
Here, '快' describes the speed of running, meaning 'fast' or 'quick'.
跑得快才能赢。
Running fast leads to winning.
In this expression, '快' is part of a fixed phrase '快乐' which means 'happy'.