You will use this column where NO OTHER column header describes the expense payment.
As this column has no description of the expense, you will need to add a description to describe the payment.
The purpose of having a description is to create an understanding of what the transaction represents. That's so you'll know what the transaction was for, when you're asked in the future by your accountant or even yourself.
The DESCRIPTION field is COMPULSORY, so you CANNOT move to the next transaction until it is completed.