help with fixing Jekyll project

I am currently having issues with my Jekyll project and need assistance resolving it as soon as possible. Specifically, I successfully set up my Jekyll pages a while ago, but after doing some modifications yesterday the website now looks weird and I get some error messages when I run bundle exec Jekyll serve. If you have prior experience with Jekyll projects, and possess strong debugging, I look forward to hearing from you! This I quite urgent, but I think it should be solved in 1-2 hours by someone who has some knowledge of Jekyll.