probably easiest explained here:
https://www.investopedia.com/terms/c/commercialpaper.asp
I haven't dealt with it in awhile, so this could be old news, but basically commercial paper is a short term investment many small businesses would make with their nightly cash balance, to earn some extra interest.
An example would be, a business would deposit cash daily into their account and at a certain time, the bank would sweep the cash out of the account into commercial paper, that would mature at some time in the future with interest.
If you have ever returned something and the company told you it would take them a few days before the funds showed up in your account, those funds were likely deposited in their commercial paper account where they earn some interest on it, before sending it back to you.
It has probably changed since I last worked with it.