please can you give us more and better details:
- provide the link of the tutorial you followed (the link is a downsized image - thumbnail)
open a terminal and write the following command and then show us what it says
sudo apt update & sudo apt upgrade
again, open a terminal and write the following command and then show us what it says
cat /etc/apt/sources.list.d/spotify.list
it looks like you have a failed gimp installation and that image isn't showing us all what's happening
sometimes a previous faulty installation does not allow another one until it's fixed, but the image showed us that you have the command sudo in a sources.list file, that's wrong and you should fix that
you can install the latest spotify using snapd
https://snapcraft.io/spotify
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EDIT: The result of the cat command is two lines of text, and both say "sudo apt-get update".
Use this command, you did something wrong following the tutorial and the file is wrong
sudo rm -fr /etc/apt/sources.list.d/spotify.list
If you want to install spotify, use snap
https://snapcraft.io/spotify
If you don't have it (snapd) follow the link
https://docs.snapcraft.io/core/install-elementary-os
cat /etc/apt/sources.list.d/spotify.list
There must be something wrong inside that file..