It's an example of a ridiculous task: Take a hippopotamus and put it into a refrigerator. They are saying that an interviewer might ask you to imagine and describe the steps you would take to do a task that you have never done, and (hopefully) will never need to do.

Yes, this seems to be a basic comprehension and problem-solving question. Alex is correct. I would like to add, that you will need one huge fridge, to fit a hippo. Unless you butchered it first.

Now I understand what she said in this article. Thank you, Alex !

I think this is the full line what will you say if they ask you to explain, step by step, how you would get a hippo into a fridge? in my point of view " how you would get a hippo into a fridge?" stand for a thing that interviewer would like you to explain.