What's wrong in my PC?

Question

Hi! I'm new user of linux and self-taught. I totally haven't got a clue what does it mean. I've scrolled Google and I couldn't search how to solve this problem. It means, I've searched similar ones, but they don't help me. Is there a huge problem? I am worried that it will make me learn badly.

sudo apt-get update

Stary:1 http://archive.canonical.com/ubuntu focal InRelease
Stary:2 http://archive.ubuntu.com/ubuntu focal InRelease                       
Stary:3 http://security.ubuntu.com/ubuntu focal-security InRelease             
Ign.:4 http://packages.linuxmint.com ulyana InRelease                          
Stary:5 http://archive.ubuntu.com/ubuntu focal-updates InRelease
Stary:6 http://packages.linuxmint.com ulyana Release
Stary:7 http://archive.ubuntu.com/ubuntu focal-backports InRelease

Reading package lists ... Done

N: Skipping acquire of configured file 'partner/binary-390/Packages' as repository 'http://archive.canonical.com/ubuntu focal InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'main/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'restricted/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'universe/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'multiverse/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'main/binary-390/Packages' as repository 'http://security.ubuntu.com/ubuntu focal-security InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'restricted/binary-390/Packages' as repository 'http://security.ubuntu.com/ubuntu focal-security InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'universe/binary-390/Packages' as repository 'http://security.ubuntu.com/ubuntu focal-security InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'multiverse/binary-390/Packages' as repository 'http://security.ubuntu.com/ubuntu focal-security InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'main/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal-updates InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'restricted/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal-updates InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'universe/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal-updates InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'multiverse/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal-updates InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'main/binary-390/Packages' as repository 'http://packages.linuxmint.com ulyana InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'upstream/binary-390/Packages' as repository 'http://packages.linuxmint.com ulyana InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'import/binary-390/Packages' as repository 'http://packages.linuxmint.com ulyana InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'backport/binary-390/Packages' as repository 'http://packages.linuxmint.com ulyana InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'main/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal-backports InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'restricted/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal-backports InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'universe/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal-backports InRelease' doesn't support architecture '390'
N: Skipping acquire of configured file 'multiverse/binary-390/Packages' as repository 'http://archive.ubuntu.com/ubuntu focal-backports InRelease' doesn't support architecture '390'