I will guess that you are referring to the green colored pencil icon that looks like it has been followed by a superscripted little red exclamation mark.
If so, that appears to be an indicator that your article has been edited by HubPages with changes made. You can click on the green pencil with the little red exclamation mark and it will open a page that allows you to view changes. The changes will show as red and green highlights to the changed areas.
If that mark is not what you are referring to, then
I had about a dozen changes made in the last few days, mostly edits to the comments area. Only one was to the text of the Hub article itself, and it deleted a full section. I was ok with the editor pulling that section out, as it held dialogue meant only for the editing staff anyway.
All the other changes were to comments that had been added after the article was written. They corrected bad spellings that we have no control over editing for spelling correctness anyway. This has been a long time concern for those who have concerns about “bad marks” against their writing because of poorly worded comments. Only one of the current set of corrections was a bad correction, so overall the editing effort improves the HubPages environment, at least for those who hold grammar and spelling as a valued quality of a good environment.