Best and Simple solution to follow:
Select the range of the columns you want to be copied to single column
Copy the range of cells (multiple columns)
Open Notepad++
Paste the selected range of cells
Press Ctrl+H, replace \t by \n and click on replace all
all the multiple columns fall under one single column
now copy the same and paste in excel
Simple and effective solution for those who dont want to waste time coding in VBA