The beginning parenthesis highlight for a brief period when you type the ending parenthesis. The matching pair will also highlight as you move the insertion pointer past either a beginning or ending parenthesis. Excel successfully converts the text to numbers. The text in quotes is not accepted as a valid number format. The text within the quotes is accepted as one of Excel's valid date formats.
References identify cells or groups of cells on a worksheet.
This is the sheet reference telling the sheet where the desired data is located. This is a separator which separates the sheet reference from the cell reference. This is the cell reference. This can be a relative or absolute reference. You can either type or select these references.