how to sum of column at end of data when i print the sheet

So try putting this formula in the next column, with the sum range equal to the entire other column.

As long as no data you don't want to sum will appear lower in the column. If this is not the case, you could name the range using an offset formula.

In cell B1, formula =SUM(A:A) will sum the entire column A.

Firstly, I see that you are from India and assume that your native language is not English, so I will share that using the term "dear" in this context, when you tell someone they are wrong in an electronic format can be perceived as condescending, or talking down to them. I will assume that was not your intent, but take the opportunity to explain the possible cultural interpretation of your statement.

If you require that this be in the same column in the next row after your data ends, you'll have to use a macro. I am not an expert in that field, so I'd repost this question in the VBA/Macros category. If you'd be OK with it being in the next row but in the next column over, you could write something in cell B2 like =IF(A2="",IF(SUM($B$1:B1)=0,SUM($A$1:A1),"")), and drag down the entire row. This would telll the formula to do the sum if the cell to the left and the cell above are both blank. This would only show the sum in the row after your ends.