Translation:电脑在桌子上。
What does 上 means here?
To be above of an item = 在+ item + 上 So it means above of, on
On, up...
Why do you include 在？
在 is used to show the location of the subject (电脑)
电脑在桌子上边 shàngbian is a more proper way to say it I believe
