Well, they could display PRINTs of text, but usually you use a SUB for that. Functions receive parameters passed to them and return ONE result normally. I have seen functions return more than one value by using a parameter also.
SUBs can return multiple values and must be called.
A Function can use INPUT, PRINT, etc. It can also fill an array. The Function name returns the value desired. It can pass strings or any type of number.
FUNCTION Average!(num1%, num2%, num3%)
sum% = num1% + num2% + num3%
Average! = sum% / 3
END FUNCTION
PRINT "The average is:"; Average!(one%, two%, tre%)
Ted