快…了【kuài … le】

快…了 says something is nearly here. 快要…了 is the same pattern with 要 added and means no more than it does without.

With a number, it means "almost"

This is the use that separates 快 from 要. Put it before a quantity and it says the figure is nearly reached.

要…了 cannot do this – tā他yāo要sān shí三十suì岁le了 is not how you say it.

No time phrase

Like 要…了, this pattern refuses one. míng tiān明天kuài快xià yǔ下雨le了 is wrong. Use 就要…了 when there is a date.

With adjectives

快 on its own

As an adjective 快 means "fast", and as an adverb it means "hurry up". 快点儿 is what someone says when you are slow, and it is unrelated to this pattern.