$21.08 is an example of a currency Number format in Excel
Step-by-step explanation:
For items like currency, one can format numbers in cells in Excel.
To view all possible number formats, click the Dialog Box Launcher attached to Number on the Home tab in the Number group.
In the Format Cells dialog box, in the Category list, click Currency or Accounting.
In the Symbol box, tick the currency symbol.
In the Decimal places box, insert the number of decimal places.
Employed for common financial values and presents the default currency figure with quantities.
Ctrl+Shift+$ is a shortcut to represent currency values.