Hi KD12,
Glad to have you joining us again in community. I can absolutely see how this sort of thing would be useful for telling your customer's invoices apart. At this time, an invoice description column isn't something that you can add to your invoice list. You can add a few other columns to the page when you're viewing transactions under your customer's profile (through the Customer section). Play around with those to see if there's something that'll help you tell the invoices apart. On that page, simply click the small gear icon just above the list and check off the options you'd like to include. Perhaps something such as the Memo option could be of use as you'd be able to add a little note there that could help you recognize the invoice.
Otherwise, feel free to leave the product development team a message by going to the Gear icon in the upper right of your account, then Feedback. It's a great way to share with us the features you're looking for in the product.
You know where to find us if you have more questions! Enjoy your weekend.