在上 (zài shàng) is a Chinese expression that means "on" or "above." It is used to indicate that something is located on the surface of something else or in a higher position.

For example:

这个盒子放在桌子上。 (Zhège hézi fàng zài zhuōzi shàng. ) (This box is on the table.)
这座山峰海拔最高的地方有五千米在上。 (Zhè zuò shānfēng hǎibá zuì gāo de dìfang yǒu wǔqiān mǐ zài shàng. ) (The highest point on this mountain peak is 5,000 meters above sea level.)

In Engpsh, you could say "on" to describe the same location or position.

For example:

The box is on the table.
The highest point on this mountain peak is 5,000 meters above sea level.

You could also use "above" to describe a higher position, as in the second example.

I hope this helps! Let me know if you have any other questions.