It depends on your keyboard layout, but it is the apostrophe key. On US-intl keyboard the ` would be together with the tilde (~). On the spanish keyboard, as far as I can tell, it would be between the Ñ and Ç.
i press " ` " but nothing" happens
Your best option probably is to go to hotkeys configuration and rebind it to whatever key you want, it could be the same.