Welcome to the forum!
So to start, what version of Zorin are you on? 16/17? Pro/core/lite? And what were you doing prior to this that ended up making this error appear? Was the system functioning properly, and now is not after some updates / an application install? Or is this a new install that hasn't worked since installing?
Sorry for all the questions, but need a little more to go on before we can start digging into reasons for this showing up.
Please answer questions above and edit your forum profile to indicate the ZorinOS edition e.g. Pro, Core, Lite etc. That will help us help you in future.
From your grub> prompt: See if this helps: Zorin OS stuck at Grub error - #3 by Aravisian