快要(kuài yào) - about to, soon going to, on the point of in Mandarin

快要 (kuài yào) marks the imminent future: something is on the point of happening. It sits in front of the verb and almost always takes a sentence-final 了, so the frame to memorise is 快要 ... 了. Drop the 了 and the sentence sounds unfinished to a native ear.

The trap is a specific time. 快要 cannot appear alongside one, so 明天三点快要开会了 is wrong. When you name the hour, switch to 就要: 明天三点就要开会了. Rough rule: 快要 for "any moment now", 就要 when you can point at the clock. In fast speech 快要 often shortens to plain 快 (天快黑了), which is fine and very common.

It also does duty for approaching a number or a state, which English handles with "nearly": 快要三十岁了, 水快要开了 (the water is nearly boiling). Note that it is about arriving, not about speed. 他快要走了 means he is about to leave, not that he leaves quickly.