Is it possible to edit a screenshot?

Since screenshots are images, the data on them cannot be edited through any standard means, but you can edit a screenshot in many ways using a simple and free image editor.

How do I edit a screenshot in Ubuntu?

Install And Use Shutter On Ubuntu

A new terminal can be opened by pressing CTRL+ALT+T in your keyboard. To take a screenshot use the Selection tool. Select the area you want to grab and hit Enter to take the screenshot. After you have taken the screenshot you can edit it with the shutter’s editor like shown below.