@Jis09 It's difficult to relate the formula shown in the picture to the underlying data, but it seems that the formula just returns zero. Not an error. If you are referring to the yellow icon with the exclamation mark in it, that's just a warning. What does it say when you click it? I suspect it says that you have inconsistent formulas in adjacent cells r something like that.
Delete what you have in cells C3:C7. Select C2, press F2 and then enter. to confirm the formula. That should copy the formula down the entire column of the table.