use excel to calculate the table range using month-from-date text

OK, so I found an answer, combining the above answer by Variatus with an additional new row.

 |   A  |     B     |     C     |      D    |
1|      |   Jan-20  |   Feb-20  |   Mar-20  |
2|      |JAN[Labels]|FEB[Labels]|MAR[Labels]| <- =UPPER(TEXT(B1,"MMM"))&"[Labels]"
3|Apple |     5     |     7     |      3    | <- =COUNTIF(INDIRECT(B$2),$A3)
4|Pear  |     7     |     2     |      9    |
5|Orange|     1     |     3     |      3    |

So formula in B2 makes an uppercase text value of the month from B1 plus the column name Labels. The formula in B3 (and down) counts the number of instances of the fruit from the named table & column shown in B2.