This video shows how to use the Resynthesizer plugin to do a Heal Selection (GIMP's equivalent of Photoshop's Content Aware Fill) in order to remove the fence from an image.
Here's the original video that this is based on: • Remove Fence with 3 Simple Steps in P...
The original image: http://bit.ly/2tHeUnd
The resynthesizer plugin: https://github.com/bootchk/resynthesizer (Note on Ubuntu it's better to "sudo apt install gimp-plugin-registry")
Music: https://www.bensound.com