Following Google's content update, explained on this page, the "originality" score in Frase was created. The "originality" score will compare the content in your editor to the content of the top 20 Google results pulled into Frase, and will flag any content in your editor that is too similar to content appearing in Google's top 20.
The circle at the top right of the editor will show the number of sentences in your editor deemed too similar to the SERP, and the right-side panel will also display the original content from the SERP. Clicking the circle will show and hide this right-side panel.
Note: you can click the "editor highlighting" checkbox to underline your editor's content that has been flagged.