I hope you are well today and thank you for your question.
It seems from your shared screenshot that you have imported the demo content created using the Unyson page builder so please use the Unyson page builder to edit it.
You can use multiple editors on your website but please note that you can only edit the page using the same page builder that you used to create it so if you have used WPBakery or Unyson or Gutenberg or any other page builder then please use the same page builder to edit the page.
Do not switch between page builders or else you will lose the content so choose the page builder that you want to use initially when you create the article content.