IFERROR() is a function in Google Sheets that helps to handle errors that can occur in a formula. It checks whether a formula returns an error and if it does, it returns a specific value instead of an error message.

The syntax of the IFERROR() function is: IFERROR(value, valueiferror)

The first argument, "value", is the formula you want to evaluate. The second argument, "valueiferror", is the value you want to return if the formula returns an error.

For example, let's say you have a formula that divides two numbers, and sometimes the second number is zero, resulting in a "#DIV/0!" error. You can use the IFERROR() function to display a custom message instead of the error message, like this:

=IFERROR(A1/B1, "Cannot divide by zero")

This will display the result of the division if it's not an error, but if it is an error, it will display the custom message "Cannot divide by zero".