  The COUNT function returns the count of numeric values (i.e. numbers or dates) within a supplied set of cells or values. 
  The COUNTA function returns the count of nonblanks within a supplied set of cells or values. 
The Excel Counta function returns a count of nonblanks within a supplied set of cells or values.
The function is commonly used to return the number of nonblank cells in a range. However, as well as ranges of cells, the Counta function can directly received arrays of values, which are not stored in cells.
The syntax of the Excel Counta function is :
Where the arguments, value1, [value2], etc, can be any values or references to cell ranges.
In Excel 2007 or 2010, you can enter up to 255 value arguments to the Excel Counta function, each of which may consist of any number of cells or values. However, in Excel 2003 and earlier, the function can only handle up to 30 arguments.
Note that, if a cell contains an empty text string or a formula that returns an empty text string, this cell is counted as a nonblank by the Counta function.
The following spreadsheet shows two examples of the Excel Counta function used to count nonblank cells in one or more supplied cell ranges.
Formulas:
 Results:

The following spreadsheet shows an example of the Excel Counta function, with the values supplied directly to the function.
Formula:
 Result:

Further examples of the Excel Counta function can be found on the Microsoft Office website.