Apple numbers User Manual

 Dictionary of Functions

 

The COUNTA function counts the number of arguments and referenced cells that are 
not empty.

COUNTA(value, [value, . . .])

 value:  A reference to one or more cells or an argument containing a value.

Notes
To count only cells or arguments that contain numbers or dates, use the COUNT 
function.

  

Given the following table: 
  

COUNTA(A1:E1) returns 5.

COUNTA(A2:E2) returns 5.

COUNTA(A3:E3) returns 5.

COUNTA(A4:E4) returns 5.

COUNTA(A5:E5) returns 2.

COUNTA(1, "a", TRUE, FALSE) returns 4.

COUNTA(1, SUM(4, 5)) returns 2.