In phpfunctions.php you have passed some values to a function as arguments. You can also pass the values back and this is known as returning a value.
Open phpfunctions.php and add a new line under the echo. On that new line put (that is a zero):
Save both files and try phpfunctions.php and it should work as before because you are not using the returned value. If you get errors you did something wrong.
In phpfunctions.php in the middle block of PHP add $returnedValue= to the beginning of the first saySomething() line and add this line after it:
echo "<p>Returned value was $returnedValue</p>";
Now when you load that page it will report the value which originated in the function. You can use the same principle to send values into a function and get the changed value back out.