What is this programming question asking for? (I don't understand what it wants)?

Write a function named liquid() that has an integer number parameter and
reference parameters named gallons, quarts, pints, and cups. The passed integer represents
the total number of cups, and the function is to determine the numbers of gallons, quarts,
pints, and cups in the passed value. Using the reference parameters, the function should alter
the arguments in the calling function. Use these relationships: 2 cups = 1 pint, 4 cups = 1 quart,
and 16 cups = 1 gallon.