This function returns the result to date of evaluating the formula of which it is a part (in other words the result as far as that evaluation has got). Its main use is together with the STYLE() function to apply selected styles to a cell depending on the cell contents.
The example returns 6. The formula is calculated from left to right as: 1 + 2 equals 3, giving the result to date when CURRENT() is encountered; CURRENT() therefore yields 3, which is added to the original 3 to give 6.
The example returns A2 + B2 (STYLE returns 0 here). If this sum is greater than 10, the style Red is applied to the cell. See the STYLE function for more explanation.
The example returns choochoo.