On some questions the edit button is greyed out and I can't edit them. Why is this, and does it happen to other people. Example: "open in terminal" command in ubuntu 16.04, doesn't open terminal in changed directory
Someone else already submitted an edit, but it is still awaiting review.– SethJun 8, 2016 at 0:41
This happens due to the system; it means that there is an edit already awaiting approval.
If you later have more reputation (over 2000) you will be able to review the edits right there and choose action accordingly.
You might want to have a look at this post which happened earlier today:
Editing a post when there is already an edit waiting for review