What does “–” mean in Excel

The “–” is a double unary operator. It’s used to change the sign of the value twice.

If you use them for numbers, it doesn’t make a lot of sense, because you will end with the same number that you had before the operation.

5 = -(-5)

This operator is a shorthand method to convert TRUE and FALSE to 1 and 0.

-TRUE = -1
--TRUE = --1 = 1
-FALSE = 0
--FALSE = 0

You can use only one minus for FALSE because zero is neither a positive or a negative number.