to have one's work cut out

1 To have your work cut out for you simply means you have a lot of work ahead of you, or a very difficult task. In other words, it can be used to remark on how much work the listener has ahead of them, i.e. how busy they're going to be, or how challenging and difficult the task is. In either case, depending on the speaker's tone, it can also have a nuance of «I sure don't envy you!». 

Here, Billy's comment basically means Wow, you've got A BIG JOB ahead of you!
___________________⦿ Yikes! | An exclamation that expresses mock horror at the sight of something difficult, horrible, shocking, scary, etc. — especially when the speaker's relieved it's happening to someone else and not them.⦿ You can say that again! | Another way of saying THAT'S FOR SURE! after someone says something that's undeniably true.⦿ all the parts are there | This is how we express that NOTHING'S MISSING

Nina comes home from IKEA with her dream bed. Her roommate, Billy, comes home to find her sitting on the floor surrounded by bed parts.


Billy: Yikes, I can see you have your work cut out for you

Nina: You can say that again! It took me a half hour just to make sure all the parts are there. 

2 When said by someone in authority like a manager or a teacher, this phrase can also imply that the listener should WASTE NO TIME in getting to work on a big or important assignment.

Nicky, a photographer, works for a magazine. His boss gives him an assignment.


Boss: Nicky and June, can you come into my office? I have an assignment for you.

Nicky: Right away, boss.

Boss: There's going to be a demonstration on Main Street today at 10am. I have it on good authority that the police is going to break it up at 10:15. I want pictures of everything — the protestors, the police, the arrests, the injured, everything! And a full story on my desk by noon. Now, you have your work cut out for you. I suggest you leave asap

Here, the boss is basically telling them «you have your assignment, SO DON'T WASTE ANY TIME».
________________⦿ to have something on good authority | to have learned or heard something from a reliable source⦿ story | A journalistic assignment in which a reporter writes an account of a newsworthy event to be published in the paper or broadcast on the news.