Yes, you can definitely copy multiple columns and paste them under a single column in Excel. Here's how you can do it:

1. Select the columns that you want to copy. You can do this by clicking on the column header of the first column, and then dragging your mouse to select the other columns.
2. Once you have selected the columns, right-click on any of the selected columns and choose "Copy" from the context menu. Alternatively, you can use the keyboard shortcut "Ctrl+C" to copy the columns.
3. Now, select the cell where you want to paste the data. This will be the top-left cell of the single column where you want to paste the data.
4. Right-click on the selected cell and choose "Paste Special" from the context menu.
5. In the "Paste Special" dialog box, select "Transpose" and click on "OK". This will paste the data from the multiple columns into a single column, with all the values appearing one below the other.
6. If there were any blank cells in the original data, they will also be pasted into the single column. To eliminate the blank cells, you can use the "Go To Special" feature. Select the column where you pasted the data, and press "Ctrl+G" to open the "Go To" dialog box. Click on the "Special" button, and then select "Blanks" from the options. Click on "OK" to select all the blank cells in the column. Now, right-click on any of the selected cells and choose "Delete" from the context menu. In the "Delete" dialog box, select "Entire row" and click on "OK". This will delete all the blank cells from the column, leaving only the values that you copied from the multiple columns.

That's it! You have now successfully copied multiple columns and pasted them into a single column, eliminating the blank cells.