What is the meaning of the phrase 'Hold water'?

You want to know the price of something so you say, ____ ?

"The writer would _____ coffee for next two weeks."

The managing director hit the nail on the head when he said the company's spending, is outrageous and unethical. The phrase "to hit the nail on the head" means:

Fill in the blank with appropriate word, phrase and clause(s): Do you know why her mother...sad?