Skipping acquire of configured file 'main/binary-i386/Packages'

Please tell me what I'm doing wrong. I just installed the Linux Ubuntu on my computer and still don’t understand anything about it. I tried to install PostgreSQL and pgAdmin. I installed on this video tutorial https://www.youtube.com/watch?v=Vdzb7JTPnGk. I get this error. Text of error: `Skipping acquire of configured file 'main/binary-i386/Packages' as repository 'http://apt.postgresql.org/pub/repos/apt focal-pgdg InRelease' doesn't support architecture 'i386'`  Tell me please how to fix it. My version of Ubuntu: Ubuntu 20.04 LTS.