A function does a very specific job within a spreadsheet.
For example, SUM will add up a set of numbers for you. AVERAGE is another common one which will give you the average of a set of numbers.
A function can be used withing a formula such as =SUM(A1:A5)
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Spreadsheet Functions