The developer console is a tool in your browser which stores a lot of information that could help us solve some issues that you may be experiencing.
If we have asked you to provide a screenshot of your developer console, here is how to do so in both Firefox AND Google Chrome:
Instructions for Chrome:
For opening the console in Chrome, use this keyboard shortcut: Cmd + Option + J (on a Mac) or Cmd +Shift +J (on Windows).
As an alternative, you could right-click on the webpage and click "Inspect," and the developers window will appear. Click the "Console" tab in that window.
From here, you can take your screenshot of whatever you need.
Instructions for Firefox:
To open the console on Firefox, use the keyboard shortcut Ctrl + Shift + K (on Windows) or Ctrl + Option + K (on Mac). The box will show up at the bottom of the browser window.
As another alternative, under the header Tools in the Mac menu bar, navigate to the sub-menu Web Developer and select Web Console.