一、only, uniqueness

1、In some sentences, this meaning is best translated by the English word ‘only’:

我身上就一块钱。

I only have one dollar.

2、In some contexts, 就 conveys precise identification of a noun phrase. If the noun phrase is a person or place, there may be no English equivalent for 就。

-我找李文。-我就是。

-I'm looking for Liwen.-That’s me.

3、If the noun phrase is a specifier or a directional expression, jiù may be translated as ‘right’ or ‘precisely.’

药房就在街角。

The pharmacy is right at the corner.

二、”一……就……structure.

“expressing events in quick succession with "一+event 1 + 就 +event 2“

我们决不能一有成绩就自满。

We must not become complacent over any success.

一坐车就晕，我得坐在前面。

When I ride in a car, I get carsick, and have to sit in the front seat.

他一见到她就爱上了她。

As soon as he saw her, he fell in love with her.

你一说我就明白了。

I understood as soon as you said it.

三、就 usually precedes negation, but it may also follow negation.

这件事不就我一个人知道。

As for  this matter, it is not just I who knows.

Wow! this is a difficult question. truly as a chinese ,I don't know how to explain it. even we use it every day.

but i can give you some examples.

就是;就要。when you want point out or declare something.example:我是第一。VS 我就是第一。

就业。that means you have a job.example:我已经毕业了，但还没有就业。

1. do → 「從事」

2. approach → 「就近」、「避重就輕」

3. succeed, complete → 「成就」「造就」

4. immediate → 「就要」

5. obey → 「遷就」、「我們就原來的計畫進行」

6. only → 「就剩下這一個了」

7. modal → 「這就對了」

The most common meaning is "exactly." Ex: 就是他偷走我的皮夾( He is exactly the person who stole my wallet.)