c# recursion check if even

I need help understanding this. I really don't understand this piece of code and could someone here explain exactly what happens?

So this is the code:

static bool IsEven(int n)
{
    if (n == 0) return true;

    if (IsEven(n - 1))
    {
        return false;
    }
    else
    {
        return true;
    }
}

And then I do this:

Console.WriteLine(IsEven(10));

How does it actually work? If I enter in number 10, it prints out true. If I enter number 7, it prints out false. But I don't understand why it even works.

It checks if the number is 0, then it returns true. But I entered 10 (which clearly is not 0) and it still print out true. Then it checks number -1.

So that would be 10-1, which is 9. But how does it know that 9 is NOT even? (it returns false).

I don't understand this code, but it works. I am so confused honestly.