When you first start using functions, you'll probably use a single function in a cell. But as you become more experienced with functions, you'll find you sometimes need to use multiple functions to perform the calculations you want.
When you need to use two or more functions together, you can nest one function inside another function. For example, if you need to return the current hour, you can nest the NOW() function (which returns the current date and time) in the HOUR() function (which returns the hour from a given time in 24-hour format; change the cell format if you need the hour in AM/PM format):
As with formulas, you can nest functions many layers deep if you need to. Here's an ...