COUNTA simply counts the number of nonblanks in the range(s) you specify and
any values you input as arguments. In your case there is nothing in D2:D4
and you specified one other argument. Therefore the result of 1 is correct.
You could put anything in cell d3 and the result would always change to 2.
You can even insert a value that results in an error (like =NA() or =1/0).

As Dave mentioned, I think you are using the wrong function. If you want it
to count the number of cells in D2:D4 that contain "jones" use this formula

=COUNTIF(D2:D4,"Jones")