With Keyboard Shortcuts installed, you will be able to bring up a Help Screen overlay at any time in any page by simply pressing the hotkey combination SHIFT+ALT+H .
The Help Screen shows you an overview of the available shortcuts (hotkeys and actions), which is useful to have a quick reminder of the shortcut required to perform each command - especially if you changed the default hotkeys with your custom ones.
It also provides you with a quick link to the Keyboard Shortcuts Plugin Settings, by simply clicking on the cog icon on the top right.